Icon Library - description from Softdepia.com:
ICON LIBRARY is a collection of more than 10,000 colorful icons which have been categorised into 150 different groups. Many icon collections available today are not classified into groups and often contain thousands of duplicates. There are very few duplicate icons in ICON LIBRARY so you don't waste your valuable time or disk space. ICON LIBRARY includes an "icon viewer" program which helps you to easily find icons in the collection, look at them in ordered groups, and extract any icon from the library for use in your computer or application.
Icon Library is a "Free to try" program. You can download and try it for an evaluation period.