Dungeon Tiles
Dungeons & Dragons Dungeon Tiles are a pretty nice product. They're packs of six full-color, attractively illustrated, double-sided, heavy cardboard "punch-out" tiles of varying shapes and sizes that can be arranged to create a "dungeon" setting for your D&D combats. The cardboard is of a good quality, the sort that high-end boardgames use for their cardboard pieces. Very sturdy. The dungeons rooms and corridors are conveniently tiled with five-foot square blocks of stone, so it's easy to tell how many spaces your figurine can move during an encounter, but even those places like outdoors, where it's just grass and dirt and rocks, little cross-hairs mark the corners of the "squares". These are really great. I actually used to do this back with 2nd edition D&D, using tiles scavenged from some Games Workshop game ("something-quest?").
An individual pack is nice, but really you probably want at least two, and maybe four or five to give you a good range of pieces. Fortunately, you don't have to buy four of the same set. Beyond the first "Dungeon Tiles" product, they've also made "Arcane Corridors", which has a bunch of magical stuff, "Hidden Crypts" which has alot of coffins and tombstones and the like, and "Ruins of the Wild" which has more outdoor places like campsites, fallen towers and just plain grassy knolls.
The packs run $9.99 US, which is a decent price, I think. Like I said, the images are pretty well-painted and the die-cutting seems to line up properly on the ones I have. This product is a nice touch if you're in a hurry, don't have your battlemat handy, or really just like the "prettiness" of it all. Some of the images, like the half-buried bones of a giant, can also act as inspiration for an adventure all on thier own.
On the downside, you're going to need a box or something to keep these in, and it's sometimes a bit of a pain to find the tile you need while you're putting your masterpiece together. Of course, if you've got any nack for organization at all, it probably isn't a big deal.
So overall, yay! Dungeon Tiles are a handy way to accessorize and add a bit of mood and flair to your D&D sessions. (I imagine there's nothing keeping you from using these for D&D minis games as well, though the "rough terrain" isn't marked with a little triangle like it is on D&D minis maps.)