Lets settle this once and for all. I've heard both are actually correct. Is the usage contextual?
Another example:
There are myriad reasons to.....
There are a myriad of reasons to.....
Unless I'm mistaken both are acceptable and in use, but don't necessarily refer to the same thing. Myriad people, for example, could refer to a diverse makeup of people, and not necessarily a large number of people, whereas a myriad of people would seem to be referring to a numeric value more explicitly.