I've been reading some posts at Nano-reef.com and there are many people there with great setups that are much more simple than the suggestions here. Granted, a skimmer, refugium, 6000 watts of light, and dsb will only help out your tank, but there is less of a need for this on a nano. Frequent water changes will do more for you than a skimmer/refugium/dsb. 72 watts of PC lighting seems to be a standard amount of light for a standard 10 gallon. This will allow you to keep basically anything you want (I have heard of people keeping clams with this light, and may try it myself). I'm about to start a 10 gallon and this will be my setup: 2 powerheads, some rock, little bit of sand, 72 watts PC light.