As a miserly photographer, I very much appreciate the generosity of others. One particularly generous person I have learned to rely on is Gavin Seim and his http://seimeffects.com presets for Aperture and other platforms. SEIM generously offers samples of his presets. I particularly find his black and white presets to be very helpful. Nik software has rave reviews but out of the price range of the miserly photographer, particularly one like myself who makes no money from his hobby. “Free” is a much better deal. Presets are even better because I don’t have to open another application, a conservation of time!