We've used Adobe Photoshop and ImageReady quite a bit for our team graphics. We've also used Microsoft Publisher(?) to make posters and such that we then print out on our large format printer. Our biggest problem is finding the files after they're made as people tend to save them to their school accounts.
Flash can be good for websites (very interactive and graphically pleasing) but keep in mind that some peoples computers might not be able to run Flash.
