Not sure how many of you know about this product, but it is a very useful tool. Basically, it is a very nice GUI front engine to the powerful panotools correction program that also includes a data file of lens corrections, even zooms, and uses the exif data to apply the necessary corrections automatically. Also corrects vignetting and chromatic aberrations.
Anyway, IF you want perfect rectilinear corrections from most any contemporary lens, including fisheyes, then I encourage you to check it out. The download includes a standalone version, CS3 plug-in, LR plug-in and Aperture plug-in as well as some actions and data files. Mac or PC. Oh, and the cost is $15 -- : http://epaperpress.com/ptlens/index.html
Here is an "examples" page: http://epaperpress.com/ptlens/index.html