Crooked Staff Website which has a number of free tiles, some adventures, maps, and even some cool odds & ends.
Then you have the newer Crooked Staff Blog, which is mostly more map tiles and ad/links to their RPGNow and DriveThruRPG pages.
For me, the Crooked Staff maps are hit or miss. I do love the free map tiles from their old site, especially for use with online games. The tiles are bright and simple, which works great with programs like MapTools or Roll20.