A really great source of information, articles and free resources:
Remember that Royalty Free is not the same as free. These sites are great resources for free photos. Proper free, as in free, free, although look out as there may be some licencing restrictions:
And of course:
We love fonts, you love fonts, everybody loves fonts, and free is the best price, so are here are a bunch of links to a whole heap of great free fonts.
A decent free vector is hard to find but some good places to start are down below:
A great free hand-crafted set of icons for UI mockups