I wonder what those numbers are based on…seems a little skewed to me
It seem to mostly based on SEO - Search Engine Optimization and hits. Makes sense as more hits can result in more traffic and advertising potential. That's why zombo.com is so high, it gets piles of hits/links/viral marketing.
They actually list how they come up with the score:
CP Combined Domain Name Appraisal Value Score: 303
Zombo Domain Name Appraised: zombo.com It has been determined based on search results that this name may be extensively valuable beyond the scope of the LeapFish.com domain analysis tool. It is recommended that you seek the services of a complete domain appraisal company rather than rely on this estimate.
Combined Domain Name Appraisal Value Score: 3622