People who like the simplicity of the Memcached protocol will enjoy hacking a client library for the super fast Beanstalkd message queue.

http://xph.us/software/beanstalkd/

Sure, it's non-persistent and similar things could be hacked with the viciously fast Redis DB or other Key/Value DBs, but it's fun to telnet into a message queue and issue plain ascii commands :-P

> but it's fun to telnet into a message queue and issue plain ascii commands

You can do this with Redis too.