Nahuel Belich describes and shows two different methods [via blendernation] for dealing and eliminating rendering anomalies in Blender when using the Cycles Render Engine.

…I came up with a solution on how to deal with Fireflies and Black pixels created by Cycles automatically! All the magic happens in the compositor…

There are times when rendering with Cycles, that you may see some artifacts in the rendered image, what Nahuel calls “fireFlies” in his tutorial. Nauel proposes that you are able to use the Cycles Clamp option, or treating the image in post by using the Blender compositor. Check out the BlenderArtists forum thread for more input on Removing Cycles’ Fireflies here.