http://www.readmytweets.com

It's essentially like a banner exchange but applied to tweets with CAPTCHAs to ensure that people actually do read the tweets.

Also see this discussion:

http://groups.google.com/group/twitter-development-talk/browse_thread/thread/c4820fbb9bb296d7

How would you cheat in this service? Do you think many people would bother? What are methods to detect cheating (without making the CAPTCHAs stronger)? I could ban IPs with suspicious activity or perhaps just rate limit the number views any user could get.

BTW, I have built this using the Google App Engine and plan to launch in 2-4 weeks.