Thanks in no small part to Joi Ito, I've set ninjafish up with a better way of archiving our entries. Granted, he basically told me to RTFM, but he did it in a genuinely nice way, and that's what really matters, isn't it?
For the record the string I'm using for the individual entries is:
<$MTArchiveDate format="%Y/%m/%d"$>/<$MTEntryTitle dirify="1"$>
Pretty neat, I think. Now that I've tinkered a bit more with MT 2.64, I'm thinking of adding a Creative Commons license and replacing my standard MT search with a Google search via the Google API. It's about time I put that dev key to some use, I figure.