I also dabble in Pownce and Jaiku.
And I use Twitku to post to all three (Twitter, Jaiku, and Pownce) in one shot.
Mostly, I use Twitterfox to post to and follow in twitter.
Using twitter, I have been posting events to my Google Calendar.
And adding todos to RTM from twitter too.
Reference: Twitter, Jaiku, Jott, Plazes, Tumblr, Yurbo, and More...
For a list of the social software/sites that I dabble in, see: http://ericherberholz.googlepages.com/social
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