memcache for MySQL
Brian Aker of MySQL AB released version 0.3 of memcache_engine for MySQL. memcache_engine marries in-memory object caching engine memcache (originally developed by Danga Interactive) with SQL query capabilities, basically enabling you do to SELECT/INSERT/UPDATE against your cache servers. The source is pretty light - take away the make files, and it’s just ha_memcache.cc and ha_memcache.h with round 25k worth of code.