Series that left you hanging

I just saw this question elsewhere and thought it would be a good discussion topic.

For me:
Many series by CLAMP, to the point where I don’t care for their stuff at all, but the main ones are Legal Drug (aka Drug & Drop) and of course, X.

I dunno what the excuse is for Drug & Drop, but they dropped it right at the climax. Originally when Legal Drug was 3 volumes long, they said it was like 1/3 done, but then I think they changed their minds because they released 2 volumes of D&D and it seems like it’s close to ending. Hopefully some day they’ll remember it and give it a half-assed ending at least. I just want to know what happens to Rikuo and Kazahaya at the end.

Also,
Sora o Daite Oyasumi by Kyuugou
Butterfly Baby By Jaryuu Dokuro