I made a bit more progress on the book-signing front. My RSS generator produces valid RSS/1.0 now. I still need to add a bunch of things to it (it's just stock RSS 1.0, no DC, no mod_event, nothing), but it works. There's a sample online now, but don't depend on it quite yet; I'm going to break it at least once before it's complete. It's kind of big; it currently includes 75 events, not sorted into any particular order.
I also added a database-driven CGI for each event; the RSS links to it. I did a bit of extra cleanup, too, so I now have better URLs for Third Place Books events.
Next up, I'd like to generate .ics files for individual events via CGI (mostly trivial), produce better RSS, produce static RSS for each bookstore, and then start in on more dynamic stuff, like recommendation-driven filtering.