TrueTwit is a Twitter validation service that verifies the humanity of those who follow you. Here’s how it works:

• You sign up for a free account a TrueTwit.com
• Any new followers receive a Direct Message (DM) requesting validatin through a unique link
• The follower then must fillout a CAPTCHA form showing they are human, not a bot
• When they validate, you receive an email that a human has followed you

Any new follower that is already registered with TrueTwit.com is authoirzed immediately. This may cause some problems as the spammer may just sign up and then spam.

The only failing the site is still in BETA and some features are not available, like removing the automatic follow other TrueTwits. If you plan to sign up at TrueTwit.com – don’t choose automatic approval [a checkmark in your signup]. There may be followers you just don’t want to follow back.

UPDATE: just DM’d with Chad Brandt, A consultant and software engineer working for Kettle River Consulting as Developer on TrueTwit.com, and he informed me that the feature for changing the auto follows “will be in the admin area today or tomorrow.” [as of July 18, 2009]. You can follow Chad on Twitter or visit their blog at http://www.truetwit.com/blog/.

If you are looking for a great way to stop Twitter Spammers, then I suggest you check out this free and powerful tool. TrueTwit.com

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UPDATE: I personally stopped using TrueTwit as it seemed to hinder more than help – at least for my account. My account seemed to stall – getting only 3 new followers in a month, so I have decided to manually monitor my account. I believe TruTwit is still a good choice for many, and highly recommend it as a deterrant from spam follows.