Necromancer Games is set to release a book called "The Mother of All Encounter Tables". It includes creatures from the MM and the Tome of Horrors, and encompasses various terrain types from deserts to arctic forests, as well as caravan generation, random events, etc. It will be about 128 pages.
I use the random encounter tables that came with the FR DM screen.
At least until something better comes out or i stop being lazy and convert the encounter tables from the World of Greyhawk books.