I try to post reviews of gaming materials I like and use. Here is another one, prompted by a question on an post earlier this year.
For more reviews, see my consolidated reviews page.
Battlemats & Megamats
Manufactured by Chessex
Over fifteen years back, I got tired of using printed out white mat sheets for our hex-based GURPS tactical combat resolution. So I purchased a number of Chessex Battlemats and a Megamat. If I recall correctly, I got them as factory seconds, not spiffy new ones. We've used these mats ever since.
The mats feature either 1" hexes or squares, or, for the reversible ones, 1" hexes backed by 1" squares. They're markable with water-soluble pens. They are very durable - they'll stand up to a lot of wear, and as long as you roll them properly, they unroll and flatten out easily.
The maps also have a clear edge - you can't easily lay two end to end to make a larger map. However, if you play most dungeon-distance battles out with miniatures the maps will have you covered.
One downside to the mats is that the water-soluble ink doesn't come off too easily. Once it's been on for a while (a few hours, certainly), it can be difficult to get off completely. You'll end up needing to swipe the map with a rag and cleaning liquid a few times to get it really ink-free. Generally I've abandoned marking them and go with placing terrain and markers on them.
You can see these in action in most of my game session pictures.
Overall: These are amongs the best gaming purchases I ever made. We use out mats so routinely that we keep one on the table at all times. We use the big one for big battles. My only complaint is the difficulty of really getting all of the wet-erase marker off. Highly recommended.