FeedTweeter
Feedtweeter is a little service that allows you to link Twitter and Plurk to your other activities.

Ever thought it would be handy to have your Plurks automatically send to Twitter (and the other way around)?
Ever felt the urge to have your blog comments sent to you by SMS?
Ever wanted to post your del.icio.us bookmarks to Twitter?

Then maybe this is a service for you.

Feedtweeter is currently in development and is in "closed beta" as it is called.
At the moment feedtweeter focuses on getting your Plurks to Twitter and the other way aound in a sane way, but it (should) work with any RSS feed.
If you want to try it out, search around for an invite code or send me a tweet at @steffest

August 11, 2008:
Sorry about the downtime and echoes.
Twitter is behaving like a drunken lama parrot.
Twitter2plurk support will be offline until a workaround is in place.

July 4, 2008:
Feedtweeter can now monitor your Identi.ca posts too: Post something in Identi.ca, and it will appear in Plurk and/or Twitter too. (with a few minutes delay)
Setup your Identi.ca account in the "My profile" section.

July 3, 2008:
Feedtweeter has added Identi.ca to the spice-list: Post something in Plurk or Twitter, and it will appear in Identi.ca too!
Setup your Identi.ca account in the "My profile" section.

July 2, 2008:
The closed beta opened up some more: you can now use the public invite codes to create new accounts and share the public invite codes with the world.

June 16, 2008:
Feedtweeter now support posting messages on Plurk too!
this means you can now have a full 2-way sync between plurks and tweets.
Write something in Twitter, and it will appear in Plurk too.
Write something in Plurk, and it will appear in Twitter too.
Your replies to other messages are not re-posted and feedtweeter makes sure your messages won't end up in an endless feedback loop.

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Feedtweeter is made by Steffest. It's free to use and comes with no warranties whatsoever.
Feedtweeter is not affiliated with twitter.com or plurk.com.