For about $20 (copper's quite a bit more expensive since then!), I built a very unobtrusive wort chiller that attaches to the stand under the first tier. Apart from the hose-barbs, it's completely made of copper with sweated joints. The internal tube is a 3/8-inch copper tubing. The external pipe is 3/4-inch copper, sweated together with tees, 45° elbows and end caps.  Take a look at the two pictures on the stand page and you can see that the chiller's ends are under the kettle and how it wraps around the frame of the stand.

Clean the copper and barb really well with sandpaper, then flux the joints properly and you shouldn't have a problem. You might have to build up a couple layers of solder where the hose barb comes through the end cap, though.

I usually water the yard with the outflow while I'm chilling a batch. Since there's a lot more water than hot wort, the water isn't really heated very much at all and by the time the water finally hits the ground, the air has robbed it of any excess heat it had.