Biomed students: there is a cool poster "Innate immunity: sensing and signalling" available via this page at Nature. The preview on that page is merely a subset of the full thing.
Immunology was certainly much easier to study back in the 70s!
BTW: In my day, the cheat sheet treasure biochem lecturers never told you about (but was kept on walls inside our labs) was the Boehringer biochemical pathways map. It was a thing of rare beauty, and now available for on-line browsing here (or via Metabolic Pathways thumbnails and Cellular Processes thumbnails. Let me know if anyone know if the paper versions are still available for postage and handling.
NEW: Cell Migration Posters and searchable knowledgebase (free access).
BTW: Please add a comment if you know of similarly cool freely accessible stuff for biomed students.