Twellow is a directory of people on Twitter. As of this writing there are over 613,000 people in the directory. The directory allows you to find individuals in your same industry or niche. It is free to get listed and you can select up to 10 categories to be listed in.
Tip: The profile you create will pull in your personal URL from Twitter as a dofollow link. You can also add additional dofollow links to the bio by entering in http://www.yoursite.com. No HTML needed. It will convert this into a linked URL. The profile will also allow you to add additional dofollow links to your online profiles as well.