How do I create generic images/avatars like SO?

Question

These profile images that each new user on here SO gets. How are they made? I mean, are they randomly generated somehow? I could use something like that.

Answer 1

This linux command will generate random identicon:

$ curl -s "http://www.gravatar.com/avatar/`uuidgen | md5sum | awk '{print $1}'`?s=64&d=identicon&r=PG" | display

Answer 2

They are gravatars ("Globally Recognisable avatars.") Gravatar is a free web service.

See http://www.gravatar.com/.

Setting up Gravatars on your site is easy; you don't even need an account! Plugins are available for leading blog software and content management systems, and our tutorials will have you running Gravatars in no time.