Here are a few that I've watched and enjoyed:
Aquarium Girl
Buzzer Beat
Akaiito
Boku, Unmei no Hito Desu (I'm Your Destiny)
Koe Koi
Omotesando Koukou Gasshoubu
GTO
Koshoku Robot
Koibumi Biyori
Sekai Ichi Muzukashii Koi
Okitegami Kyoko no Biboroku ( a mystery drama)
Nigeru wa Haji da ga Yaku ni Tatsu (I Married as a Job - where the popular "Koi Dance" came from)
Momikeshite Fuyu
These are ones I haven't watched yet but I hear a lot about how good they are:
Code Blue (3 seasons worth)
Date: Koi to wa Donna Mono Kashira
Gokusan
Koishite Akuma
Love Shuffle
Piece
Proposal Daisakusen aka Operation Proposal (This is the same as the Korean one which I forgot what it's called in Korean)
Reverse
Tokyo Tarareba Musume