Django aggregate functions which operate conditionally (i.e. generate SQL
CASE statements) ...useful when combining aggregate functions with a
GROUP BY clause. eg
ExclusiveBooleanField which is a boolean (database) field where only one row in the table (or optionally, a subset of rows based on value of other fields) is
True and all the other rows are
Django cache backends supporting CAS (compare-and-set) operation. Memcache, Redis and Dummy backends. CAS allows updating a value without risk of race condition bugs.
An eBay API client which respects
XSD schema and talks
SOAP, but doesn't use Suds. With a clean and simple interface and low memory usage (unlike Suds+WSDL...).
An extension of the Python stdlib's
calendar.HTMLCalendar that makes use of Django templates to customise the output. After all, it's pretty lame having hard-coded HTML output.