Some of the links in my previous Twittermap did not work anymore, so this is an update. I have also tried to cut down redundancies and to focus more on simplicity and usability.
Remember, this is not intended to be an extensive list of Twitter apps, classified by some arcane pseudo-scientific criteria (if you need something like that, you can go here). I have tried to select the most useful Twitter related sites / apps and to order them in a logical manner (these are, in fact, the things that I actually use in relation to Twitter).
Similar mindmap: Gramo OS 2.0
p.s.: Yes, I would like to hear your suggestions! 
