I did the Developing Enterprise Windows®-based Applications with .NET: Rich Client--Visual C#® .NET test... It is a very nice test and after you complete the test it gives you an assessment on what should you learn/invest your time learning... I have to say, it wasn't an easy one :-) But I could see from the test that I should learn more about working with unmanaged code in C# (I didn't learn it deeply enough...). Anyway, there are many tests over there, tests in: SQL Server 2005, Windows 2003, VS.net 2003/2005, Office, BizTalk Server 2006 and much more... you should check it out