Nicely parodied in The Sweetest Thing.
One of my favorites is the palace coup montage from The Scarlett Empress.
I also love any montage where people are building stuff, improvising, working with hardware, and getting ready for a fight. Example: Arney preparing to get it on with the big scary alien in Predator.
The Sweetest Thing, you forgot the part in that montage where the Wacky Gay Friend puts on a wacky outfit and gets a head shake from both girls. (Always near the end of the montage.)
I love the time passing montage from Notting Hill. I don’t see how it could have been done in one take, just presented as one. Several characters in the movie come through at different points in different costume. Then there’s the woman that gets progressively more pregnant and has a baby at the end. There’s no way that could have been one take unless I’m missunderstanding what you mean by one take.
I agree. It’s very deftly edited, and Hugh Grant walks past in the foreground while the seasons pass behind him, but it wasn’t one continuous take, IIRC.
I commented when I first saw that movie that one scene would make a great stand along video for the song. Also, the climax of the movie to the cover of “Mad World”.
Speaking of Hugh Grant, the airport montage at the beginning of Love Actually gets to me, of course because of the voiceover.
I’ll second the tournament scene from Karate Kid. Classic. Along with the aforemetnioned montages from Rocky III & IV. Decent montage in the most recent one, but not as good.
Nice, rom-com style romantic montage in The Naked Gun, and Farelly brothers have done some funny ones.
At the end of Part I or II from Spike Lee’s Katrina “Requiem”, there’s a montage mostly comprised of dead bodies, some floating. I forget what was playing, maybe a jazzy dearth, but it was moving.
Come to think of it, there’s a nice montage at the beginning of Oliver Stone’s JFK. Kinda like “the Cold War in three minutes or less.”
Lost had a funny end-of-episode montage in one of the first episodes. They went in for the montage of everyone settling in to life on the island, with some pop song playing in the background. As we see a shot of Hurley sitting on the beach listening to his CD player, the music stutters and stops unexpectedly. Hurley looks at his CD player and says, “Damn.”
Obviously the batteries had run out, and he had no way of getting more. 
I loved that one, but I was hoping that the end of the cd player meant the end of the cheesy montages. Guess not.
The closing montage of the Futurama episode, Jurassic Bark.
The middle 20 minutes of every “A-Team” episode. They perfected and distilled the art of the montage into pure dead-horse-kicking.