As for high-school romance:
14 Sai No HaHa - actually it's not even high school, and its pretty serious, but it's a very well played drama about important issues.
Brown Sugar Macchiato - sometimes silly, but cute. I did enjoy watching it.
Gokusen- the main story is not about romance, but there is usually an episode or two about it
Kimi ni Todoke -nice story, but slow-paced, I liked anime more.
Lovely Complex - it's too adorable to miss, a must watch!
Mei-chan no Shitsuji - surrealistic, very shoujo-manga style
Proposal Daisakusen -one of my favorites, although while first time watching you get the "OH, just say it already!" feeling, everything makes sense later.
Samurai High School - love story is only hinted really, but the show is too great not to watch.
Yankee-kun to Megane-chan -cute and fun, and Narimiya is a great actor
Yamada Taro Monogatari - more a bromance, than a romance but some love story is thown in as well and it's rather funny.
College dramas (but some are on high school level really):
Tatta Hitotsu no Koi - many consider it a most romantic jdrama ever, and well... she is a student, so it counts as collage drama.
Smiling Pasta, personally I think it was a cute drama and I really like the soundtrack.
My Mighty Princess - I enjoyed it so much! It's fun, it's romantic and quite unpredictable.
Hi My Sweetheart - quite enjoyable and quirky romance
Hot Shot Anime-like basketball with love triangle.
