Yeah, right now I think the plan is to make a nice chiller for my next couple of extract batches in the smaller kettle that I have, then I'll build another immersion chiller for the larger kettle--when I do full boils, I'll run water through the smaller chiller while it sits in a bucket of ice water, then run the cooled water to the larger chiller in the actual wort.
Checked out the therminator plate chiller they sell at BkHomebrew but, as sexy as chilling my wort in 7 minutes sounds, the clean up involved doesn't sound so nice. On the other hand, the space I'd save is pretty attractive...