If you do not wish to go for BRS or First aid or stuff like that, i guess you are left with the standard text books.
Among the text books, the short yet complete ones would include Snell's Gross Anatomy, Barr's Neuroanat, Ganong's Physio, Lippincott's Biochem - for the preclinicals.
Lange's Concise Pathology by Chandrasoma & Taylor is a good concise text. So is Lippincott's Pharma.
For Microbiology, you cannot go below Kruckshank.
For non-medicine clinical subjects, CMDT gives a good concise overview, though medicine itself is as long or short as any other text book.
(Appleton Lange books are the best concise texts for any subject.)
I don't think you can go shorter than these. But anyone knowing better plz correct me, i too am always on the lookout for shortcut books.