Sadly, since I was away from a computer with ADB on it, I was forced to Nandroid back to a prior state and lose any progress I had made on my project. I still have no idea what was causing the problem, but I needed a phone more than I needed to know what was going wrong at that moment.
Enter Live Logcat Lite, an application that replaces your bootup animation with a more-or-less live log of what is going on during boot.
While some diagnostic bootup apps display pre-recorded animated boot information (they're just a fancy animated boot screen installer), Live Logcat Lite displays the same information you get
In addition to it being a great diagnostic tool, it's a good way to be able to see that your EVO is booting up correctly and you're not waiting five minutes to pull the battery.
Live Logcat Lite is free, but if you like it you can pay $2 for the full version, which has some extra features.
Links: Market (EVO) | Market (web)