I've done this with regular vinyl tubing, and it does help some, but a copper coil or direct circulation of ice water would be way more efficient. In fact, I'm probably going to go with direct circulation with a pump in the near future.
On Deck: Jamil's Vanilla Robust Porter
Fermenting: Orange Blossom Mead
Kegs: Element 56 Pale Ale, Ron's Belgian Blonde, Summer'n Saison, Furloughktoberfest '09, Grateful Pale Ale, Sam Adams Cream Stout Clone, EdWort's Apfelwein