I've bought AF-confirm chipped adapter rings for C/Y, Oly OM, and Leica-R for canon EOS on eBay from
big_is and
happypage_hk, and been really happy with them, although I think that happypage_hk is putting his chips on fotodiox pro rings, which makes them have a much better fit than big_is's. I also like that they're painted black. Both sellers now offer programmable chips, where you can set the max. aperture and focal length on the chip.
Chipped adapter rings, if you're not nervous about using them, have the advantage of giving you autofocus confirmation feedback, and if you're adapting to four-thirds (bonus!) you retain in-body stabilization. Also, your EXIF will be less empty. Whether it will be accurate is another issue.
