but I'm not sure about the config. phpMyAdmin will obviously require php and a webserver too. Unless you plan on hosting other web content I'd probably just use Lighttpd rather than Apache (as the TKL MySQL appliance does). However most instructions seem to describe a LAMP setup so that may be an easier way to go.

The Ubuntu Server Guide will probably be invaluable and there's a pretty good looking "Perfect Server" tutorial. If you wish to go with Lighttpd you'll have to have a google, but there should be plenty of info out there.

To be honest though, I think I'd just stick with your current setup. If you're running them on separate hardware and want to consolidate then perhaps you should look at installing a hypervisor type OS and run them as separate VMs.