My Agfa SnapScan 1212u is about 10 years old now, but had been working perfectly through every OS X release. With the Update to Snow Leopard, however, the old app ScanwiseX wouldn't start anymore. The error I received was "ScanWise couldn't find ColorSync-Systemprofile."
To get my scanner working again, first I installed the OpenSource files from TWAIN SANE. First I installed libusb.pkg, then sane-backends.pkg, and finally sane-preference-pane.pkg.
With the freeware Scan Again for the SANE Extension (Scanner Access Now Easy), I could finally use my Agfa SnapScan 1212u again. After launching the app, it bounces a long time, but it will eventually work. There are not many preferences, but enough to do all important scans I need.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20091216155248868