As part of my server reorganization, I'm once again maintaining sitemaps on scripting.com.
There's a single sitemapindex file that links to all the sitemaps.
I also released the code that generates the sitemaps, running in the OPML Editor. Here's a source listing.
Update: When the nightly backup code runs it also produces a JSON file listing the URLs of files that changed since the last time it backed up. It's stored in a calendar-structured folder.