Thomas Knoll the lead programmer on Photoshop has released a nice little utility to extract all sensor data from digital camera RAW files. Normally the edge of a cameras sensor is excluded from the creation of the file because of possible colour errors when demosaicing etc. However! if you have a particularly tight crop and would really appreciate the extra pixels then download the utility from http://www.luminous-landscape.com/ You will need to convert your raw file to DNG before using this utility. A free DNG converter is available from http://www.adobe.com/.
The image here is a crop from the extreme right hand corner of a file that shows the recovered pixels that were not in the normal RAW conversion (hand coloured in brown to illustrate the area recovered).