Schaum's Outline of Differential Equations, 3rd edition (Schaum's Outline Series) (Repost)

Very helpful if you are looking for a set of worked-out ODE problems; a bad idea if you are trying to learn the subject, or refresh your memory. PS. Holzner's "DE for Dummies" is one nice cheap beginner book - but I would still go for a "regular" textbook.