Summize is excellent. You can set up an RSS feed on your start-up name and then it feeds you Tweets that mention it. It is a great way to connect with early adopters who use your site.
<a href="http://www.techcrunch.com/2007/12/17/summize-a-sentiment-engine-for-the-reviewosphere/" rel="nofollow">http://www.techcrunch.com/2007/12/17/summize-a-sentiment-eng...</a><p>Seems like they just went more real-time with their "review" analysis... still a cool concept. And they're funded by betaworks.<p><a href="http://betaworks.com/work.html" rel="nofollow">http://betaworks.com/work.html</a>
If you are interested in this, you may want to check out our site as well:<p><a href="http://twist.flaptor.com" rel="nofollow">http://twist.flaptor.com</a> to see trends<p><a href="http://twittersearch.flaptor.com" rel="nofollow">http://twittersearch.flaptor.com</a> for real-time search