Here's a post for a great stand; it'll be overkill for a 55 gallon, but change the 4X4's to 2X4's, and determine your own measurements (length, width, height).
Otherwise, google search images (55 Gallon DIY Stand, etc) or use the DIY forum in here. Lots of great ideas. With a 55 gallon, you don't have to worry about an overwhelming amount of weight, so it's a lot easier.