at first, we were using nails, but at this point, if i buy 2 cars on cards, i might spend an hour making room for them. we call it "tetrising"...
i move things so often, there would have been a million nail holes in the walls...so i bought "display boards" from Elmers (the glue people). They sell the display boards at office max, but they arent cheap. they are made to fold open, but i keep them folded shut, and when folded shut, they are slightly thicker than the length of a thumbtack. i think that those boards are around 10 bucks a piece, and to cover the walls, it took something like 15 of them...i believe. but the nice thing, it allows you ALOT of freedom with how youre going to hang things. with nails, you get one chance, and there is a hole..with the display boards, you can keep on moving them until you like the layout. the display boards are nailed to the wall, with 4 aluminum roofing nails...