I have a couple of different ideas here, so bare with me as I try to get a feel for what you are looking for...
#18: this was my first idea: it instantly shows at a glance what you are about, and it could function great as a stand alone icon on anything from printed work to web.
#19: is a very dry/clean take on my second idea. It is straight to the point and will make people instantly think of the tall flag poles.
#20/#21: my personal favorites! I added some flag-type motion to the text and dropped it onto a flag pole. This one will be great at virtually any size: from large signage down to tiny print work (like magazine icons or letterheads)... I especially like these because they capture some of the athletic spirit of USC as well. It very much feels like something you might see on a student's shirt around campus, and it is obviously very important to appeal to that crowd first and foremost.
Let me know what you think, and we can go from there. Thanks!