If you are a Mac user (and Web designer), then you maybe use the Markup Validator S.A.C. — this app is a stand-alone version of the W3C Markup Validator. The new icons from Veerle could replace the default icon of this application in your MacOS X dock.
Plus, she is releasing the icon set for free to the community!
Unfortunately, the icon set is available for Mac users only. It’s a pity, because I think that these icons could be used in many more ways… Of course, you can use the JPG variants (which are high quality), but without the optional alpha transparency, which is available in the PNG format only…
If you want to use any of the icons on MacOS X, a link for download is available in the Veerle’s blog post:
(There you will also find instructions, how you can change the icon of Markup Validator S.A.C. in the dock of MacOS X.)
As to the JPG variants, you can copy them manually from Veerle’s blog, or download them as one ZIP file, which I made for my own convenience (as the icons are released for free):
Finally, what can I say? Another great design from Veerle! :-)
[UPDATE] Same icons, but in PNG+alpha file format. Cool! :)