gmail tasks is way too one-dimensional. workflowy is cool, the closest i've seen to an idea i've had in my back pocket for some time, so thanks for the tip and i'll try them out. however, no mobile client.
Lack of mobile client drives me nuts, but I love Workflowy. It's my meeting note-taking notepad, my to-do list, my scratchpad, and about a half dozen other things. Absolutely indispensable.