Duplication of effort or evolution?

Dear LazyWeb,

I need help compiling a list of Python modules that exist outside of the standard library and either duplicate or serve as replacements for modules that are in the standard library.

For example, simplejson became the standard library module json but is also maintained separately for backwards compatibility and to include the optional C extension that is not part of the standard library version (please correct me if I’m wrong).

Another example is httplib2, which is meant to have more features than the standard library’s httplib.

If you know of other similar modules, please post links in the comments. Thanks!