Roundup : twtrip, JustSignal, Twalala, TweetBackup, Tweetag
twtrip - a space to list your trips (each trip has its own page), and it will match other tweeps who will be or are in the same destination. Tweets you make on that day will display on your travel page…also add a widget on your blog.
JustSignal - post to both Twitter and Friendfeed. Filter the noise on Friendfeed or on public twitter (also see Monittor and PeopleBrowsr) by only displaying posts and comments that contain keywords of your choice. You could probably do this on Friendfeed search…I can’t remember…and maybe something the outstanding Peoplebrowsr could incorporate.
BTW, PeopleBrowsr is a brilliant Twitter interface, as you can create group streams and search within them, and you can search within your friends stream (and make them new streams)
[via m]
Twalala - a website alternative to Twitter that allows you to filter out keywords and even mute noisy tweeps
TweetBackup - back up your tweets incase Twitter has a melt down 
Also try Tweetake and TwitterSafe
Tweetag - search a keyword, and it then displays a keyword cloud of other common words used with your keyword query, you can then add any of these to your query.
[TC]
BONUS
CelebrityTweet
![email.png](http://services.nexodyne.com/email/icon/GxbiQvgbwBgCnw%3D%3D/oIp%2BJMQ%3D/R01haWw%3D/0/image.png"){kind=icon}
