VueScan is an easy-to-use scanning program that works with most high-quality flatbed/film scanners to produce scans that have excellent color accuracy and balance.
It also has advanced features for restoring faded colors, batch scanning as well as a multitude of features professional photographers often use. It changes nor installs anything on your system or your operating system and all other installed scanner software will continue to function normally.
With VueScan, you can scan documents, photos, and film, then easily create PDF, JPEG, TIFF and TXT files as well as import files directly from Photoshop - for those times that an image may need some polishing beforehand. It also includes support for more than 1500 scanners making it a versatile scanning utility.
Version History for VueScan: http://www.hamrick.com/vuescan/vuescan.htm
Limitations: Limited by the number of supported devices and watermarking.