I've got mine running pumps, heater, and lights. I'm only on a 29g Biocube with very, very limited space (no room for an ATO, no sump, no fuge >.<)
EVENTUALLY I'll have somthing along the lines of a 180 and I'll use it to run all of the above + ATO, automatic water changes, automatically start (and stop) an RO/DI unit, control dosing pumps...maybe a wave generator or two. But that's years down the road and I'm sure there will be more cool stuff out.
I'm actually having trouble getting the dimmer to work, and it's beyond frustrating.