Here's first a quick list from one pass over the docs. I've attempted to limit myself to a few like you've suggested, though I'll wait for confirmation that Raymond is not willing to simply add them to everything once we're at it :).

http://docs.python.org/library/difflib.html
http://docs.python.org/library/stringio.html
http://docs.python.org/library/codecs.html
http://docs.python.org/library/stringprep.html
http://docs.python.org/library/datetime.html
http://docs.python.org/library/math.html
http://docs.python.org/library/cmath.html
http://docs.python.org/library/decimal.html
http://docs.python.org/library/itertools.html
http://docs.python.org/library/os.path.html
http://docs.python.org/library/csv.html
http://docs.python.org/library/configparser.html
http://docs.python.org/library/logging.html
http://docs.python.org/library/getpass.html
http://docs.python.org/library/json.html
http://docs.python.org/library/urllib2.html
http://docs.python.org/library/unittest.html
http://docs.python.org/library/code.html

When I hit the docs to diagnose a problem, it's usually to take a quick look, and then to hit the source code to read that too, since most of the stuff that's in general use is common enough for me to know how it works in a general sense, so the source code is typically where I go pretty quickly after reading what the docs have to say.

It's not a huge deal obviously, hg.python.com is not the furthest thing away. Just seems convenient, especially since like I said a lot of the other ones I peek at already have links.


As for non-python modules, I really would like to say that linking to C source sounds just as reasonable to me, a little C never killed anyone :), but I don't want to push my luck, so I'll stick with whatever I can get here I guess (I know I put some non-python modules on the list).