from popular woodworking...
shop boxes, with wood i-beams.
i use the shop boxes, but just throw 2x6s between 'em. a shop box is nothing more than a box, that can be laid on any side, each side having a different height. so laid flat they're 24" tall... on another side they're 36" tall, etc... made mine out of some leftover pine and whitewood.
the more i work with these, the more i realize i f'ing hate sawhorses.
and a simple but foolproof fence that works great for plywood ('specially thin plywood)
edit:
couple more pics...
i'm thinking of making the wood i-beams... much stiffer/straighter than a 2x6... and i use the shop boxes more often than my workbench ('cause the workbench is always piled up with ****)