Anyone may choose a Creative Commons license by going to http://creativecommons.org/license/
Several services are available to integrate license selection into a website or application:
Requires minimal knowledge of HTML.
Documented at http://api.creativecommons.org/docs/readme_15.html#simple-chooser or merely go to http://api.creativecommons.org/rest/1.5/simple/chooser for the simplest invocation, which obtains a list of license URIs and names in the form of a select list (which can be easily parsed if you wanted a list of licenses for use elsewhere).
Documented at Web Integration Guide
Screenshot below, example described at Movable Type.
RESTful web services API
Allows any website or application to transparently integrate CC licensing.