sad or romantic movies, series
this
Clannad, Myself;Yourself
Kannazuki no Miko and Yami to Boushi to Hon no Tabibito are my favorites in the bittersweet romance genre. If you like shoujo-ai, check 'em out.
Rurouni Kenshi Oavs. First 4, in America it was re-titled "SAMAURI X" though I refuse to call it that.
MUST see Kanon 2006.
Gungrave. I cried like a baby at the end.
REC is a good romantic series