HIV Infection Overview (from Cell's Alive!) with animations and video clips
Cell-mediated and humoral immunity - includes a good visual of different types of cells
Immune System Defender Game - well-done, and fun!
Cartoon-like illustrations - from NobelPrize.org - the cells in the immune system with clear, simple descriptions. Highly recommended for anyone who's having trouble picturing things (like me!).
Tootsie Pops = viruses: an immunologist's "dumbed-down" description of the cells of the immune system and HIV. (Not too dumbed down for me, though. I need this sort of thing to reach those occasional "aha" moments!)