Was reading up on memcacheDB and came across MemcacheQ (also on the same page)
MemcacheQ is a distributed message queueing mechanism that lives onto of - you guessed it - memcache.
So you get all the benefits of memcache's speed, portability and distribute-"ability" but for managing message queue's.
For example, you could run memcached on your server farm, post a new queue into the "cloud" and any of of your nodes can grab the best suited message for them and process it.
it's as easy as..
<?php
$memcache_obj = memcache_connect('memcacheq_host', 21201);
memcache_set($memcache_obj, 'demoqueue1', 'message body here', 0, 0);
memcache_get($memcache_obj, 'demoqueue1');
memcache_close($memcache_obj);
?>
awesome! now to find an application for it :D