FineWoodworking had an article in their Tools and Shops 2009 edition where the author described a 4 piece torsion box workbench design that I've been wanting to build forever.
Imagine 2 +very well thought out+ sawhorses (collapsable but with relatively large surface areas) on which you can lay 1-3 8' long, 9" wide torsion box beams, either butted up against each other, or seperated slightly to allow legs etc to drop through.
I can't post links because it's all behind their subscription side, but it seems incredibly versatile and can be quickly taken down and leaned against a wall or moved around.
It's no 4x8 hard rock maple workbench, but it does seem awfully handy.