I have used these opensource tools on past projects in different stages, but never all of them at once.

I am on a project now where there is a build server, Subversion, Nant, NUnit with 100% NCover required coverage, CrusieControl, CCTray and Rhino Mockc.

I was extending an Interface and concrete class in a solution I had never worked on before today. Automatic builds were turned off for the day for a special case QA test. I added my new members to the Interface, implemented them in the concrete class, did a local build, tested, all looked good, so I did a Subversion Update then Commit. 

Around 4:30PM the automatic builds were turned back on. Right away the build failed for less than 100% code coverage on my last Commit. Turns out there was a project in the solution I modified that had numerous NUnit tests on the Interface/Concrete class I modified, 3 of which now failed. Now that is cool..of course i was frustrated as i wanted to go home..but..I did a bad thing..I did not run nant on the source prior to my Commit.

Lesson learned, and a great lesson at that!