Textures and prop graphics for 2D maps, Keyword: Free Options

[Wesley Street]

Hey everyone!

This week my group will be switching from battlemats and pre-laminated floorplans with paper figures to map projections on a white board with icons for characters, vehicles and NPCs. I'm going to start by using a black and white map with a grid I created in Illustrator and Photoshop. But I would like to begin creating some (semi)professional looking maps, a la Star Wars or Dungeons & Dragons minis tiles and playmats. Does anyone know of any sources where I could pull free 2D textures and objects?

Just so you know what I'm talking about I found this as an excellent example for a sci-fi floor texture. Top down views of shelving, boxes, crates, appliances, lab tables, etc. would be great. I've looked at a lot of video game texture sites but they're mostly limited to walls, floors and 3D objects. Need some old-school, yo!

Thanks!