Ah, teen movies!
I agree with so much of what has already been said, so I'll just list my favorites (all of which I'm pretty sure were mentioned)
Clueless
10 Things I Hate About You
Bring it On
She's the Man (the part where Amanda Bines sticks the tampon up her nose? Oh my gosh

Plus Channing Tatum... is just.. he needs to marry me; that's my point)
Step Up
Center Stage
She's All That
Legally Blonde
Sixteen Candles
13 Going on 30
Say Anything
The Breakfast Club! <--- One of my favorite movies ever.
Note: One of my roommates was in my room looking at my DVD collection (I have quite a few) and she saw the The Breakfast Club sitting on the shelf and said "Ew, The Breakfast Club. I hate that movie" and I was just like

"Get out. Get out of my room." Haha. I was kidding about the get out of my room thing (kind of), but it seriously wounded my very soul when she said she hated that movie...