FLOR by Interface (the residential line of the commercial carpet manufacturer) provides you with these adhesive squares that connect four tiles together at the corners, so you don't need any adhesive on the floor. The carpet tiles are so stable once they lay on the floor that they won't shift even if they're not adhered to the floor. The adhesive squares also give you the flexibility to move the tile around or switch them to another room if you feel like it. I have carpet tile out on my screened porch, and now I'm thinking of using it in our newly painted living room (photos coming soon, I promise). Here are photos of the samples I just ordered from http://www.flor.com/ I'll keep you posted as to which one I choose.
So have you used carpet tiles in your home before?
Feelin' Groovy - Pebble
Sophistikat - Pewter (warm gray and beige, not the blue that's shown)
Ups and Downs - White (love this one)
Walk the Line - pewter (love how this is the same color as the countertops in our kitchen)
Warm Welcome - Flax (reminds me of a sisal rug)