Challenger IconDB
Challenger IconDB (Icon Database) is a database that contains icons of
various sizes and keywords attached to them.
ICONLOOK
ICONlook.com is a place where to find your icons and offers a pretty handy
interface for searching and downloading icon files.
Icons-Search
The Icons-Search is an Icon Search Engine that helps you to find quality
icons available on the Internet. You can find icons for Windows Vista and XP,
Macintosh, Linux, icons for Desktop, Software, Website, Mobile, Presentation, in
sizes from 16×16 to 256×256 in PNG format and sizes from 16×16 to 128×128 in ICO
format.
Iconlet
Iconlet is simple search engine for free icons, images. For every image user
get information about author, image resolution, graphics format and license
type.
IconFinder
Iconfinder provides high quality icons for webdesigners and developers in an
easy and efficient way.
IconSeeker
The IconSeeker.com is an icon search engine on web, it contents about 50,000+
high quaility icons and each icon has PNG, ICO and ICNS formats for Windows,
Macintosh and Linux Systems.
EasyIconFinder
EasyIconFinder is a new Icon Search Engine that helps you find quality icons
now available simple by filling in a keyword !
Free Icons Web
Free Icons Web is where you can browse and download Over 15,000 high quality
Free Icons for Windows, Macintosh and Linux Systems.
Very Icon
The VeryIcom.com is a icon search engine, it contents over 20000 high
quaility web icons in more than 1000 icon packs. Each Icon has serval file
formats such as PNG, ICO, you can free browse and download for Windows,
Macintosh and Linux Systems.
IconsPedia
Search and download free icons in PNG format. Arranged by categories, that
include animals, food and phones.
来源：http://www.hongkiat.com/blog/41-image-and-icon-search-engines-designers-should-know/