The Wizards of the Coast website offers a free utility called Dungeon Tile Mapper for GMs.

Starting with a blank grid, you drag and drop tiles from WotC’s various Dungeon Tiles products (which are quite pretty). Once they’re on the map, you can move them around, rotate them, etc.

You can save and print the maps you create, and there’s also a downloadable version available (2.92 MB .zip file). Pretty nifty.