I rarely like top-10 lists, because they usually are engineered by PR firms, not real analysis. The VAR Guy, however, has a list that seems fairly well-grounded in reality (though I think he missed some obvious ones like Alfresco and MuleSource, but then I'm biased).
A few things he gets wrong, like that MySQL customers "CraigsList, Google, TicketMaster, Yahoo" are customers "to die for." This may be true, but not in the way he thinks. This sort of company doesn't pay money for software (and doesn't contribute back code, usually). They tend to use without giving anything back. But generally speaking, I think his analysis is very good.
Take a look and see if you agree.
Disclosure: I'm an advisor to a few of the companies on VAR Guy's list. Clearly we both have good taste.