Turns out I posted too soon. Behold: Serendipity! Source of many fine random generators. The interesting site generator is exactly what I need: a spark for an interesting location-based encounter.
Also handy is the Barrel, Crate, and Sack Generator from the Tools section of the Wizards archive. I find it particularly handy for generating treasure captured from merchant caravans and the like; sometimes one needs trade goods rather than gold and jewels, and this utility provides an interestingly unusual assortment.