I got out of work early yesterday so I stopped by Home Depot and picked up a 3/8" 20 ft coil of copper and 3 2 ft long metal rods.
I wound it up pretty loosely with about 2 inches of space between coils then zip tied it to the rods for support.
I use my HLT as the storage vessel and MLT for straining the wort (I clean everything during the boil.) To do this you just swap their positions so the MLT is on top.
Attach the one end of the coil to the MLT and the other to the outlet of the HLT, fill the HLT with cold water and let it rip. I used heavy duty clear vinyl tubing which works great.
In testing, 190 degree "wort" went through the tubing submerged in a bath of 50 degree water and came out between 70 and 80 degrees from beginning to end as the cold water heated up. Still not bad results at all considering I didn't stir the cold water or anything. Flow rate is adjustable on both ends as I have ball valves on both tuns.
I realize how I described it is probably confusing so I'll take some pics tomorrow. All in all the project costed ~$30 and required no soldering or anything.