RadLab has a number of interesting effects you wont find anywhere else and, as with Color Efex, users can create recipes by combining effects.
NoiseControl 1 is a plug-in for Photoshop and compatible programs (both Mac and Windows) thats remarkably effective at reducing image noise while keeping edge details and natural grain. It can also sharpen a noisy image without increasing noise, and even add simulated film grain to an image to make it appear more natural.