Dwigger: Digg for Twitter
Dwigger is a new service that lets you not only post "Tweets" on Twitter and Dwigger, but lets other users reply to your messages in a threaded conversation stream format and vote on content, ala Digg. As long as you have a Twitter account, you're ready to use Dwigger. You can post messages directly through Dwigger, or paste the URL of an interesting Tweet you've found and post that - you can find hot Twitter posts through Dwigger's "Hit List." Of course, those Tweets that are voted on the most get put into "top voted" categories on Dwigger. Any comments (replies) to Dwigger messages will be posted on Twitter as a new Tweet.
There are some other interesting features, such as the ability to expand on the 140 character limit within Dwigger, including images or video (will be shown as a link in the corresponding Tweet) and the ability to submit content to Dwigger as an SMS message through your Twitter account by starting your message with "d dwigger."
It's a new service so there will certainly be some growing pains, but the ability to vote and keep organized conversation streams is an attractive prospect for the microblogging community.