I was just reading a post from Justin Etheredge in which he wrote "... I get so jealous when I talk to the Java guys at work and see all of the freaking awesome tools that they have for free on their platform. Since I use the NUnit, NCover, NHibernate, NAnt stack when doing most .NET development, sometimes I feel like we are just a bunch of copycats".
What other cool frameworks exist that aren't on .NET and I may not know about? Can we leave out things which have a direct or pretty reasonable analogue, just the kewl shiznit!
PS we aren't so bad. I'm pretty sure NDepend started out on .NET and has moved to Java
PPS one answer per item please! It makes it a lot easier to discuss them!