Then is time to visit TDD Problems:

The aim of this site is to contain a growing collection of software problems well-suited for the TDD-beginner to learn Test-Driven Development through problem solving.

Today the site contains 20 different “real-life” problems, which is probably enough to keep anyone busy for a long time. And since it was announced in the testdrivendevelopment list only a few days ago, it’s very likely the list will keep growing.

Enjoy!