I hit the 300 post mark. (I hit the 200 mark back in Feb). Some days I feel like I'm still going strong and other days I feel like I'm running out of ideas. It's still fascinating to see which posts get a lot of interest and which don't. It's usually the opposite of what I'd predict. What do you want to hear about?
Lately, blogging gets competition because my energy is redirected to the new "Building Development and Diagnostic Tools for .NET " forum. We recently expanded its scope from just Mdbg, and it's educational to see what sort of questions people ask there. If you're building .NET tools (especially using ICorProf or ICorDebug), swing on by that forum!