The absolutely wonderful and thorough camera review site dpreview.com has (finally) added lenses to its repertoire. Not only will they investigate lenses with the same hands-on depth that their camera reviews enjoy, but they have also rolled out a custom Flash-based, interactive widget that allows you to change the settings of the lens and view its sharpness, chromatic aberration, geometric distortion, and falloff (vignette) live (small screenshot to the right). I played with the tool for a little while and was blown away by how easily it allows you to see what the real-life sharpness of the lens is at different distances from center and at different f-stops. Amazing.
They only have four lens reviews posted at the time of this writing, but I'm sure there will be many more in the coming weeks. It can't be easy to put together such incredibly detailed analyses.