Hate to dredge up an old thread like this, but I recently got approval from the SWMBO to build a kegging setup, and thought I would also try to incorporate a more advanced fermentation temperature control system than my current swamp cooler at the same time.
I really like that glycol side-by-side system with the radiator. Seems like an easier build than the ducted air setups I've seen, and you don't have as many worries about ice that way. I already have a fountain pump that could probably do the job for the glycol loop as well. And, if you really wanted to, you could build a two-chamber version that could do lager temps in one chamber and ales in the other just by adding another fan and temperature sensor.