The documentation occasionally contains a link to the source code for a module in the stdlib. See for instance http://docs.python.org/library/urlparse.html and http://docs.python.org/library/collections.html , or many others.

With a quick perusal, I couldn't immediately guess as to which ones managed to have one and which ones don't, but it'd be convenient to have a link in as many places as possible, which is certainly more than we have now. (See e.g. http://docs.python.org/library/json.html and http://docs.python.org/library/itertools.html and many others for examples of pages that lack a link).

Perhaps putting it in a more conspicuous but still consistent location would be reasonable (the sidebar?).