It's a calculator for theoretical speed, ratios, etc for a huge number of bikes based on user input of gear ratios, redlines, tire and wheel size, and a whole load of other parameters. It has stock specs already loaded for most bikes and is pretty intuitive.
Those of you that have to quantify your fun to know how much you're having will probably dig it.
Here's what it spit out for my bike, with a 140 rear tire and 16/52 gearing.
Show us what you got!
If this is not the appropriate board, let me know and I'll repost it elsewhere.