I work in the ISV Practice here at Microsoft. There are two tools recently released to the SharePoint community that should have ISVs and Enterprise customers excited.
SPDisposeCheck provides a static source code analysis tool to check for leaks that may be caused by not disposing of SPSite and SPWeb objects properly. While most people that have worked with SharePoint know of these perils, this tool can provide a second set of eyes on your code. For those new to the product, SPDisposeCheck will allow you to uncover those instances where improperly disposed objects would result in leaked memory. Instances where this occurs isn’t always obvious, so the tool can help reduce leaks that make it to production.
Another exciting tool is the SPDiag tool. This tool greatly simplifies gathering data required for troubleshooting issues in a SharePoint environment. When working on issues or performance problems getting a good snapshot if the farm environment can help uncover the root cause of the issues quickly and get customers back to work.