Clip art, icons, graphics, etc

Greetings,

I am a software developer interested to not reinvent the wheel. I am
interested in locating a (hopefully free) clipart or image gallery
containing commonly used icons such as folders, open or closed, files,
disk images, LEDs, and so forth. Where might one find something such as
this among the plethora of possible resources out there on the
internet? Any help would be greatly appreciated.

Regards,
Michael Powell