We don't know whether JKR is hinting at something with all these watch references, or whether she just likes watches! (And she has a wrist watch on her website desktop!) Big thanks to RoCkYz21 for compiling most of this list!
Professor McGonagall pulled out a lace handkerchief and dabbed at her eyes beneath her spectacles. Dumbledore gave a great sniff as he took a golden watch from his pocket and examined it. It was a very odd watch. It had twelve hands but no numbers; instead, little planets were moving around the edge. It must have made sense to Dumbledore, though, because he put it back in his pocket and said, "Hagrid's late. I suppose it was he who told you I'd be here, by the way?"
He was ripping the paper off a gold wristwatch when Aunt Petunia came back from the telephone looking both angry and worried.
Harry lay in his dark cupboard much later, wishing he had a watch. He didn't know what time it was and he couldn't be sure the Dursleys were asleep yet.
The lighted dial of Dudley's watch, which was dangling over the edge of the sofa on his fat wrist, told Harry he'd be eleven in ten minutes' time.
Ron looked at his watch and then glared furiously at Hermione and Neville.
When Angelina had scored, Harry had done a couple of loop-the-loops to let off his feelings. Now he was back to staring around for the Snitch. Once he caught sight of a flash of gold, but it was just a reflection from one of the Weasleys' wristwatches, and once a Bludger decided to come pelting his way, more like a cannonball than anything, but Harry dodged it and Fred Weasley came chasing after it.
Chamber of Secrets
"Hermione, let me read your composition," said Ron desperately, checking his watch.
"We'd better get going," said Harry, loosening the watch that was cutting into Goyle's thick wrist. "We've still got to find out where the Slytherin common room is. I only hope we can find someone to follow..."
Harry looked at his watch. Five of their precious sixty minutes had already passed.
Prisoner of Azkaban
Uncle Vernon drained his teacup, glanced at his watch, and added, "I'd better be off in a minute, Petunia. Marge's train gets in at ten."
"We can't be there yet," said Hermione, checking her watch.
Ron looked at his watch. "If we hurried, we could go down and see him. It's still quite early..."
Hermione checked her watch. "We'd better go down, you know, the feast'll be starting in five minutes." They hurried through the portrait hole and into the crowd, still discussing Snape.
"She's seeing us all separately," Neville informed them as they went to sit down next to him. He had his copy of Unfogging the Future open on his lap at the pages devoted to crystal gazing. "Have either of you ever seen anything in a crystal ball?" he asked them unhappily.
"Nope," said Ron in an offhand voice. He kept checking his watch; Harry knew that he was counting down the time until Buckbeak's appeal started.
"Yeah," said Harry, looking at his own watch. It was now two o'clock. "Wish she'd hurry up..."
"I am going to lock you in. It is --" he consulted his watch, "five minutes to midnight. Miss Granger, three turns should do it. Good luck."
"Right, it's nearly time," said Hermione tensely, looking at her watch. "We've got about forty-five minutes until Dumbledore locks the door to the hospital wing. We've got to rescue Sirius and get back into the ward before anybody realizes we're missing...."
"D'you reckon he's up there yet?" said Harry, checking his watch. He looked up at the castle and began counting the windows to the right of the West Tower.
Hermione was tugging at his sleeve, staring at her watch. "We've got exactly ten minutes to get back down to the hospital wing without anybody seeing us -- before Dumbledore locks the door --"
"Oh, he's horrible," whispered Hermione, her ear to the door. "I bet he's all excited because the dementors are going to finish off Sirius...." She checked her watch. "Three minutes, Harry!"
"I don't want to think about it!" Hermione moaned, checking her watch again. "One minute!"
Goblet of Fire
Dudley was crammed into an armchair, his porky hands beneath him, clamped firmly around his bottom. Harry couldn't take the tension; he left the room and went and sat on the stairs in the hall, his eyes on his watch and his heart pumping fast from excitement and nerves.
"Look at the time," Mrs Weasley said suddenly, checking her wristwatch.
They trudged down the dark, dank lane toward the village, the silence broken only by their footsteps. The sky lightened very slowly as they made their way through the village, its inky blackness diluting to deepest blue. Harry's hands and feet were freezing. Mr. Weasley kept checking his watch.
"Must be nearly time," said Mr. Weasley quickly, pulling out his watch again. "Do you know whether we're waiting for any more, Amos?"
"Three..." muttered Mr. Weasley, one eye still on his watch, "two...one..."
Harry disentangled himself from Ron and got to his feet. They had arrived on what appeared to be a deserted stretch of misty moor. In front of them was a pair of tired and grumpy-looking wizards, one of whom was holding a large gold watch, the other a thick roll of parchment and a quill. Both were dressed as Muggles, though very inexpertly: The man with the watch wore a tweed suit with thigh-length galoshes; his colleague, a kilt and a poncho.
"Nearly six," said Ron, checking his watch and then staring down the drive that led to the front gates. "How d'you reckon they're coming? The train?"
So far, however, all they had managed to do was get the badges stuck on POTTER STINKS. Harry crept past them to the portrait hole and waited for a minute or so, keeping an eye on his watch.
And still they walked, Harry getting more and more irritated as he jogged along in their wake, checking his watch every now and then.
Wand tip alight, he crept along the bookshelves, pulling down more books - books of hexes and charms, books on merpeople and water monsters, books on famous witches and wizards, on magical inventions, on anything at all that might include one passing reference to underwater survival. He carried them over to a table, then set to work, searching them by the narrow beam of his wand, occasionally checking his watch...
"Ten minutes?" Harry croaked. "Ten -- ten minutes?" He looked down at his watch. Dobby was right. It was twenty past nine. A large, dead weight seemed to fall through Harry's chest into his stomach.
Where were the other champions? Would he have time to take Ron to the surface and come back down for Hermione and the others? Would he be able to find them again? He looked down at his watch to see how much time was left -- it had stopped working.
Harry checked his watch, then remembered it hadn't been working since it had spent over an hour in the lake.
One of the nifflers had suddenly leapt up and attempted to bite Pansy Parkinson's watch off her wrist. She shrieked and jumped backward.
Harry took off his watch, which he was only wearing out of habit, as it didn't work anymore, and stuffed it into his pocket. Then he picked up a niffler. It put its long snout in Harry's ear and sniffed enthusiastically. It was really quite cuddly.
History of Magic had rarely gone so slowly. Harry kept checking Ron's watch, having finally discarded his own, but Ron's was moving so slowly he could have sworn it had stopped working too. All three of them were so tired they could happily have put their heads down on the desks and slept; even Hermione wasn't taking her usual notes, but was sitting with her head on her hand, gazing at Professor Binns with her eyes out of focus.
Hermione looked at her watch. "We haven't done any practicing!" she said, looking shocked. "We were going to do the Impediment Curse! We'll have to really get down to it tomorrow! Come on. Harry, you need to get some sleep."
Order of the Phoenix
"Hes excellent," said Lupin, who was checking his watch.
"I dont know, its just what Mad-Eye says," said Hermione, distractedly looking at her watch.
"Wotcher, Harry," she said, winking. "Better hurry up, hadnt we, Molly?" she added, checking her watch.
"Just a couple of people," Hermione repeated, checking her watch and looking anxiously at the door.
A few goals and they would be in the lead as usual, Harry assured himself, bobbing and weaving through the other players in pursuit of something shiny that turned out to be Montagues watchstrap.
"So, anyway," he checked his watch, "phase one is about to begin."
"You will tell your Aurors to stop searching for my Care of Magical Creatures teacher so that he can return to work. I will give you " Dumbledore pulled a watch with twelve hands from his pocket and surveyed it, "half an hour of my time tonight "
Ron receives a heavy gold watch with odd symbols around the edge and tiny moving stars instead of hands from his parents for his seventeenth birthday.