Any ranking will put importance on certain factors which are chosen from all the possible factors by the designer of the ranking. You have chosen to rank based (I presume) on incoming links on CrunchBase. However, this is intrinsically no more impartial than a ranking based on yearly revenue, or number of employees, or size of their offices, number of mentions in the New York Times, or any other of an unbounded number of metrics.
I would argue that PageRank, while it may have done a good job of ranking websites for the purposes of search, is a pretty poor choice here. It's highly susceptible to reporting bias, where some companies will be better-represented on CB. Empirically, you also get weird artifacts, like the ranking of MySpace ahead of Apple.
Choosing a good metric requires a theoretical explanation of why that metric is important and why it helps answer your question (which you don't state, but I suspect is something like, "which are the most important startups", whatever that might mean). Just choosing something doesn't necessarily tell you anything useful.
[If you're interested in high stakes debates about rankings, look into the hoopla that comes about every year when US News & World Report releases their college rankings. These numbers can have huge effects on college's prestige and, lower down the food chain, their bottom lines.]
