I've used these on the last couple of builds and what a difference it makes. No pulling on the wheel or "Walking" the chain tight..... Just a couple turns of the ratchet and and it stays put. This particular style gives you a larger surface to tighten the wheel to the frame (No need for oversized washers). They are machined to fit in the drop out.
BICYCLE BIKE SILVER CHAIN TENSIONER ADJUSTERS PAIR NEW - eBay (item 380198467809 end time Feb-16-10 13:02:38 PST)
"Never do anything you wouldn't want to explain to the paramedics."