Hi I'm working on my own portfolio, and so I'd like to have some icons for technologies that I work with. So does anyone know of free icon sets that include css, php, c#, html5 and other web technology icons?
www.iconfinder.com should work out for you.
There's this set here: http://www.smashingmagazine.com/2010/12/23/free-icon-set-for-web-developers-coded/
Dosen't have all the languages that you are looking for but could maybe give you a head start.
If this question had by title "how to represent web technologies in icons":
You could draw or pick (from any of the other websites in the answers) a plain button with a certain color, and write the language over it with a nice text effect (shadows, glows, your preference). HTML5 has an icon, and it's a sort of shield that says html and has a big number 5 (superman reference?). You could do something similar with css, php and c+. Perhaps you could use different colors for each language.
Some psd buttons you could use as inspiration/background: