Tweexchange, once a marketplace for Twitter handles (that operated against Twitter’s TOS) is now a site where you can check whether or not the username you had in mind for your new Twitter account is still available.

If it turns out it’s not, you’ll get a list of possible alternatives. As a bonus, and thanks to a partnership with domain registrar and hosting company GoDaddy, you’ll also get to see which domain names related to your desired username are still available. Users can register or backorder domain names through GoDaddy straight from the site.

When a Twitter username is ‘pending removal’, you can also opt to be notified as soon as it becomes available (Twitter deletes usernames 60 days after their suspension). Note that the latter service will set you back $5.

The new Tweexchange is a product from Blast Applications, a New York-based developer of iPhone, Facebook and Twitter apps.