I’ve been keeping my eye out for some time now for some good, free icon resources. Here’s a number that I would like to share; remember, you can use Imagicon or IcoFX to convert any image into the ICO format in whatever icon size(s) that you need. If you want to create icon libaries check out BeCyIconGrabber.
If you would like to edit or modify your icons, you would be hard pressed to find a better free tool than IcoFX.
Vistaicons.com: contains over 2000 high quality 256×256 icons (suitable for Windows Vista) in PNG and ICO formats. Freely downloadable.
Toolsbox PNG Package Deluxe: version 6.1 features 240 (128*128) High-Quality PNG Icons. The home page seems may be down but you can download it here (3.71 megs). Iconaholic: this website has some amazing icons, wallpapers, and themes available for download; commercial use of these requires a licensing fee.
Crystal Clear Icon Pack: created by Brazillian artist Everaldo Coelho; view and download individual icons at Wikimedia commons crystal clear icons page or download collectively from the artist’s site.
Iconbase: icon packs for Windows, Mac, Linux available for download. Some of the download links dont work for some reason.
Maxpower: features a list of icons submitted by various artists, some of which are actually free (for personal and commercial use).
KDE-look.org: has a good icon section.
Icon Drawer: has a free section that is worth checking out (for personal or non-commercial use).
InterfaceLIFT: submission-based aggregator of downloadable icon sets. The quality of submissions can vary but you will find many excellent icon sets here. Check out the highest rated and most commented sections.
Iconfactory free section: keep an eye on new content added every week or so.
Freeiconsweb: offers some 15,000+ downloadable icons that you can use for personal projects; for commercial use you would have to pay a licensing fee.
AvenTenbrae: offers downloadable icon packs by Laurent Baumann, released under the Creative Commons 3.0 Licence (no commercial use). Unfortunatley its Mac format only (.icns) — if you know of a free program that can convert ICNS to ICO please let me know.
Dhtml site: this site contains links to a number of other sites with free icon sets. The collections tend to be mostly small-size 16×16 icons suited for website use.
Yellow Icon: offers downloadable icon sets with different themes such as Spider Man, MacOSX, video game characters, etc.
Icongalore: this site offers for-pay icon packages, but you can visit this page to downloads their free (and rather good) XP icon samples pack