Also available Lowe's and similar stores are kits from "2 x 4 Basics". You still supply the wood materials, but the kit makes it a snap to build a very sturdy work bench. I stuck with 8ft and 4ft pieces of 2x4 (which they cut for me at the store) to keep it simple, but you can use pretty much whatever dimensions work for you. They also have a website:
www.2x4basics.com
Look in the "storage systems" section.