PPA: https://launchpad.net/~thisfred/+archive/autoqueue

A cross player plug-in that queues up tracks similar[*] to the current one, in a semi-intelligent and configurable way (it can block playing the same track or artist for a configurable amount of time) It works pretty well in creating a consistent yet not wholly predictable listening experience. It has been made to work with quod-libet, rhythmbox and mpd so far.

[*] similarity is looked up on last.fm and/or computed from acoustic analysis if you have mirage https://launchpad.net/ubuntu/+source/banshee-extension-mirage installed.