IMHO, if youre looking for something to help you in clinical practice the Primer on the Rheumatic Diseases (by the Arthritis Foundation) is very good and so is Rheumatology Secrets by Sterling West. If youre looking for a more traditional text then Practical Rheumatology by Marc Hochberg is good. The bibles are Kelleys Textbook of Rheumatology and Rheumatology also by Hochberg. The last two are the best and also very expensive.