Since a few weeks now, I've been completely hooked to Dark Signs. It's basically a free (!!) console-based hacking simulator. The greatest part however is the included programming language "D-Script". It's largely based on Visual Basic, so if you have some experience in that field,you should feel right at home. But for those without experience in programming, it's a very easy language to master, and a great stepstone for the more "real" programming languages. Anyway, just check it out at
www.darksigns.com, and step by the forum some time.