I am now using Tact-Tiles, the 12"x12" interlocking grid that you can write on with dry-erase markers. It is great. Draw your stuff on it way in advance, pack it up and take it with you to your friends house. I got 12 different color markers from Staples for about $10, and use them all to depict things on different levels. Dead enemies become red once I remove the figure or counter so we can keep track, and other items of note become purp or another color. With 3 different greens forests really start to spring to life, and it only takes me about 15 minutes to fill all of my 12 tiles with the next encounters for the game. It's also great for using 4 tiles to depict a smaller encounter then use the other 8 for the large battle that session. I can hide each of them away until the characters discover what's behind the door that I purposely placed at the edge of one of the tiles; when they open it I pull up the tile that was leaning against the wall to prevent the players from seeing it.
Drawback: $$$. It's expensive for some people, and I was reluctant at first to pick them up in favor of a Chessex battlemap, but I gotta say I will never go back to a battlemap again.