The Hex Hack is an 'adventure landscape', which I believe is the new buzzword for 'sandbox', with nearly 350 entries, adaptable to any d20 rpg.
It has tables to start the campaign from humble beginnings, a table to finish off in a legendary location, and all sorts of random goodness in between. Many illustrations and several basic drawn hexes with lots of stuff for PCs to do/find/steal/kill/interact etc.
The Hex Hack: A d20 Sandbox Campaign
Thanks
John