Having some spare time at the moment, I took the .NET certification 70-536. It was my first first Microsoft exam and I thought it was a bit tricky to be honest. I was really confident going to the examination place, wondering if there was a special prize for 100% correct answers. That thought burned after a couple of questions, though.
I passed it eventually and I'm happy I produced something during my interlull (being between assignments as they say).
On to the next one, which might be 70-503 (WCF) or 70-562 (ASP.NET 3.5).