Here is a great list of .Net Tools.

I have run into the "Failed To Enable Constraint" exception many times while using datasets. I always find it to be a very tedious job to determine what the actual error is. Here is a good post that shows how to trouble shoot this problem.

I like to have one solution with multiple projects that compile DLL's to a common folder that all other progects reference. The problem is that VS.Net locks the DLLs. Well this article tells how to get around this.