1. A clean, neutral UI design (like Tweetie).
2. Clear separation of tweets (like Tweetie).
3. Good API support (retweets).
4. An integrated timeline (@mentions and DMs in with everything else).
5. Personal timeline search (I don’t care about public timeline search).
6. Deleted tweets get deleted on refresh.
7. New posts are made from a window, of which I can have several (like Tweetie).
8. Hidden Dock icon (like Tweetie).
9. Remembers your scroll position (like Tweetie).
10. Marks everything as read as soon as you scroll to the top (like Tweetie).
11. Shows a new tweets indicator, but without a count (like Tweetie).
12. Allows blocking from within the app.
13. Allows you to mute people and filter tweets, without completely burying them.
14. Integrated Profile/Timeline UI.
15. Bi-directional conversation tracing (does the API even support this?)
16. In-app picture viewing.
17. Infinite scrolling (like Tweetie).
18. User-extensible image and url helpers.

Does the world really need another Twitter client? It seems to be a real problem. Everybody has a different idea of how it should work. What I envision would have even less UI than Tweetie, but would support several use-cases that are important to me. Tweetie 2, if it ever happens, would fix retweets, which would probably be enough to satisfy me.

Or I could write it. I’m definitely interested in starting another Objective-C project, but I don’t know if this is really what I want to do. I’d gain more by fixing Fireworks than Tweetie.