Well, I figured that wouldn't make much difference, but I did it anyway. Then I got to looking around, since my memory was hovering around the magical 20MB mark again. When I looked at memory use with DiskUsage, I found that all the apps I'd downloaded from Amazon's Free App of the Day -- and moved to SD, and frozen -- still had massive Dalvik caches that Titanium wouldn't get rid of. Turned out that freezing them only prevented them from starting at boot. That was great, but I didn't know they were still hogging memory even while encased in carbonite. So I sent them all to the great beyond... and now I have 45MB free. D'oh! I'd say I can't believe I was that dumb... but now I've got enough experience being dumb to *totally* believe it.