WeFollow.com is a directory of Twitter users created by Digg founder, Kevin Rose. When the site launched early last year, Ben Parr of Mashable covered the story and explained how WeFollow.com works:
The premise is simple: anyone can tweet to @wefollow hashtags that represent what categories they would like to be listed under. WeFollow sees these @replies and then organizes users based on those hashtags. Common hashtags include #blogger, #entrepreneur, and #socialmedia. WeFollow only allows for three hashtags per person, assuring the directory does not become overly cluttered.
That restriction on tagging is a key component to WeFollow. It prevents the sort of keyword gaming and spamming that makes many other directories unusable.
WeFollow.com is an excellent resource for finding people who generate and promote great content, but it can also be a great resource for finding people who you can to make aware of your presence of Twitter. By following top twitterers talking about your areas of interest, you may make them aware of your tweets.
Remember, Twitter sends an email notification to folks you follow—this is the default setting, but can be turned off—a follow is also a sort of message. So, people you follow will be made aware of you, check out your tweets and profile, and may follow you back. This is how mass-follow tools like TwitterMass can help to gain you followers as well.

