Colnect uses language icon.

We are happy to see that Colnect - Collect and Connect network decided to use the language icon in their next release.

Extract
I've considered the option of using flags but have ruled it out because:
1 - Flags represent countries, not languages. Consider English which is widely spoken in the US, UK and Canada. On the other hand, consider Canada which has both English and French as official languages.
2 - Adding 25 flag icons for every page is an extra communication load with no good justification.

A solution?
An interesting project I've came across is the 'Language Icon'. They've decided to create an international icon to mean the word "language". Here it is: Classic Icon 32 x 32
It's supposed to look like a tongue though personally I don't find it resembling a tongue. If it'll catch on, however, it could be of great use to websites / application around the world. Kudos for the idea!

Read the full article here, or visit their site.