I use this one:
http://www.amazon.com/Epson-B11B2002...=epson+scanner
I highly recommend it. Aside from being fast and providing incredible clarity - it also provides software (Media Impression) that makes it easy to stay edit and crop - while also staying organized with the files.
Regarding "unsharp mask": The "unsharp" of the name derives from the fact that the technique uses a blurred, or "unsharp," positive image to create a "mask" of the original image. The unsharped mask is then combined with the negative image, creating the illusion that the resulting image has greater visual acuity than the original. (wikipedia)