I've found these very useful, generally getting two copies of each release. They're printed front and back on thick stock, with distinct designs on each side. I've stayed with 3.5 and these are now the only WOTC product I buy.
I agree that some 3-D scenery/miniatures to use with these would be helpful.
Andrew Turner(Pathfinder Adventure Path Charter Subscriber)
I like these, too. For 3D props, I go to pet shops looking for esoteric aquarium decor. A little alteration, some paint and flock, and you've got anything from lost Mayan-like cities, to Egyptian and Romanesque ruins. You can also get some foam core and make your own buildings and ruins, and virtually any of the trash in your bins can be cleaned up, filed off, glued together, painted and re-imagined into something very cool. Here's a cool article.
Insulation foam and foam core can be bought for a few dollars at Lowes or Home Depot, etc. The crystal in the middle is a green novelty lightbulb from the housewares section at Wal-Mart. It's screwed into a shoplight outlet. The thing in the center of the floor is a CD with glitter glued on, and the struts and wall pieces are broken bits of molding from an old door project.
I like these tiles. My wife bought me a couple. I don't really care for the ones that feature piles of bodies and I wish the "river" was more than ten feet wide.
I'd like to see WotC put out some terrain tiles like: all water tiles, all sand/desert tiles, all rocky/hilly-looking tiles and so forth.