Thanks to contributions from RSS4Lib readers and a bit of online searching, I’ve put together the start of a directory of legislatures (national bodies and, for the United States, state legislatures) that offer RSS feeds to track current legislation in one way or another. See Legislation Feeds for the list to date.
If you know of other legislative bodies that offer their constituents an RSS tool for tracking legislation, please send them to legislationfeeds@rss4lib.com.