TwitHawk is my pride and joy. It is a custom built web app that allows anybody to easily do target marketing on Twitter. The site uses the CodeIgniter framework, and the jQuery library.
TwitHawk is a real time targeted marketing engine that will find people talking on twitter now by your chosen topic and location, allowing you to really hit your target mid conversation with ease.
It will periodically search twitter for you and either auto-reply or generate a list of matches for you to respond to or reject from your twithawk account.
Monitor your campaigns true CPC with onsite link tracking (with a site average CPC of less than $0.02) and Google Analytics integration.
The site has been featured on such sites as TechCrunch, OneForty, CNET, WPN, Open Forum, Business Week