It actually helps having someone asking you about the code. I had reasons to revisit an old codebase I cobbled together (and basically stoipped working on) Jan-Mar 2007 and once I had had a glance at the code, it wasn't too bad, even if there's almsot no comments (I'd climb out on a limb and say "completely undocumented", but there's a few design docs and at least one protocol spec in the code tree, even if it's not in the code itself).