Signals and image processing/analysis -- Learning Resources

Illuminerdi

I'm at a mediocre university I don't belong at and can't really transfer at this point unless a great university is willing to break its own rules about deadlines for me for this fall(connections, anyone?!). I suppose I'll just have to wait for grad school (should be starting in spring '14), but this is very frustrating.

So, I'm studying signal and image processing/analysis, and the curriculum is so boringly easy. I know the material isn't really as easy as the courses I've had, so, what are some things I should know and how should I go about learning them?
Also, where should I learn them? (best schools for this discipline)
Are there youtube videos on the material or free textbooks online?
Which disciplines of math that aren't typical for a EE undergrad to take are involved in the higher level signal and image analysis, or at least would up a GRE score and help with grad school?
(I've aced the calc series, linear algebra, DifEQs, and complex analysis)