Just thought I'd share this site. I've used it for comparing the fit of new bikes with that of ones I already own. The primary measurements I use:
Reach - Will I want a longer/shorter stem?
Stack - Will I need spacers, a riser stem, or slam the new stem all the way down?
Front Center - If I'll be using larger tires, will I experience toe overlap?
BB Height - If I'll be using a 2nd set of wheels with much small tires, will pedal strike be a problem?
Seat Tube Angle - Will I need more or less setback to the seatpost?
Standover - Looking out for the family jewels so to speak.
Below is a link to a comparison of a couple of my bikes to one I'm planning to get.