I haven't really watched one recently where I was sad that it was over... Brothers Conflict I was a little bit sad because I enjoyed the characters and I wanted to know what would happen 다음 (hope there is a season 2).
I'm always sad when I finish a season of Natsume Yuujinchou. When I get done with it I just don't know what to do with my life for a few days without it. And then I just wait around and hope that there will be another season. Here's to praying for a season 5!
GetBackers T-T It was really funny, despite being an older anime, but they left it on a cliffhanger/promise for third season and never continued it. It ended in 2002... I started three other animes but I really miss Ban and Ginji. T_T