At this point, I've got what seems to be an endlessly long list of things I'd like to eventually blog about. My list includes:
(Update 10/25/05: added more hyperlinks since I've now down some of these)
1.) Brushing up on some AI: A coworker lent me Fundamentals of Neural Networks.  That should have some interesting blog fodder. This certainly could include implementing a basic neural net in C#, and then exploring making it debuggable.
2.)  Fixing the problem with the MDbg Gui on beta 2 where when you open a dialog, it throws a ThreadState exception. It turns out this is because my Mdbg gui threading isn't quite right. The quick summary is that Mdbg and ICorDebug need to be on an MTA thread; the windows UI needs to be on an STA thread, but it's really useful to call ICorDebug APIs from the UI thread to populate tool windows. I'd like to update the sample with a fix I can be proud of.
3.) Cool pet project idea: A common project is to have a simple robot kart with sensors and motors, and then you wire the logic between the sensors and motors such that the kart can follow a track. I've seen this done in both hardware and software. There's a large variety in software solutions (AI / learning techniques vs. explicitly programming it). I thought it would be cool to write a software simulator for such a robot and then let you plug in C# modules to control the robot.
4.) My experiences in hooking up IronPython to Mdbg via some Mdbg extension. (Update: Done! See here and here)
5.) More on managed PDBs stuff (like the stuff I alluded to here).  (Update: more here)
6.) Commentary on how to test something like the debugger (a subset of "How do you test Visual Studio" spawned by mentioning how big VS is.)
7.) More on new Whidbey debugging features, particularly interceptable exceptions (which are very cool when combined with EnC).
8.) Explain how an interop (mixed-mode) callstack works.
9.) Some interview tips.
10.) Explain why my code snippets are syntax colored again (for the first time since we switched to Community Server)
11.) More on MDbg: Our view of MDbg; Top N things we'd like to fix in MDbg; etc.
12.) What I've learned from video games.
13.) Problems with debugging code in dllmain (eg, why the loader lock is evil).
14.) Problems with interop-debugging and appverifier.
15.) Top N managed feature areas where managed debugging breaks down.
16.) More design commentary (specifically lessons like this and this)
17.) Random trivia posts: Difference between IL offset 0 vs. Native offset 0; Some comments above various native code-gen. (Update: Done!)
18.) Doing a mock Microsoft security review on real-life non-software processes.
19.) Comments about MC++ codegen (if you thought C#'s yield was cool...) (Update: see here and here)
20.) Commentary on debugging static vs. dynamic system and exploring the relationship between the halting problem and debugging.

Wow. That's longer than I realized and I could still keep going.