This is my favourite rack tutorial that I've yet to find. This site I find is generally good. Click on 'cages' and they've got a few more tutorials for racks of different sizes. I wouldn't call it pretty, but efficient and relatively easy to build.

http://www.arbreptiles.com/cages/iri...ris_rack.shtml

There's nothing stopping you from replacing the wood with melamine which might look nicer.