OpenMMOd is a open-source event-driven MMORPG Server written in C++ with a YAML packet definition backend. It is MySQL database driven currently with future backend support to come in the future.
elspy is an extension to the Exim MTA that allows Exim users to supply a local_scan() function written in Python instead of C. (Exim's local_scan() API lets sysadmins supply site-specific code for approving/rejecting email messages at SMTP time.)