Couple of cheap tips:
http://i49.photobucket.com/albums/f280/vintagefortytwo/IMG_1243.jpg
http://i49.photobucket.com/albums/f280/vintagefortytwo/IMG_1245.jpg

Good idea. I roll up on wood blocks all the time cause theres no way Im gettin a jack under my car otherwise...

I usually keep a couple of these collapsible milk crates (http://www.uline.com/Browse_Listing_313.asp?keywords=crate)in the back.

I didn't know about collapsable - where can you get them?