I definitely do the "want to share but also 'bookmark'" thing with my Twitter updates. And, yes, hashtags somewhat solve this, but not really - at least not for me. I like the idea of lists on Thingist, but I don't want to have to categorize all my tweets.

If Thingist could automatically categorize my updates, but have a way for me to re-organize them, that'd be ideal. Seems like a decent amount of people fall into your same use case, where they tweet quotes, songs, videos, etc. Some of these would be easier to detect than others, but it's somewhat doable.

This seems some like weird cross section between Twitter, Tumblr, and delicious to me.

I agree with you on the form thing, which is something that I'm adding within the next week (the ability to add something to a list without having to fill out the second form [this was something that the users asked for]).

That said, people are willing to fill out extra information about (look at digg, reddit, youtube, fark, etc. etc.)...maybe not for status updates, but thingist isn't about status updates.

Use cases for twitter? I get hashtagging events (I saw this first hand at the intel appup conference last week), but what else beyond that?