Leitax offers DIY C/EF non-electronic lens mount conversion sets for various mounts. The conversions have the advantage of, unlike many of the commonly available converter solutions, perfectly fitting into the camera bayonet without tilting loosely in the adapter either from the start or after a while of usage (I can fully confirm this as being a fact for Olympus OM lenses - it's not just a marketing gag). Being non-electronic, the conversion sets are rather cheap compared to professional conversions like Conurus, but still offer AF indication in viewfinder by optionally built-in Dandelion chips. Also, they are not only compatible to digital but also to older analog SLRs. And as are their "big brothers", the conversions are fully reversible. In most cases it's possible for EOS 1D series camera owners to order a version either triggering the camera's AF switch or not.
Contax N: There is a wide and a narrow mount version (depends on your lens). The narrow mount version does not triggering the AF switch in 1D cameras available (AF confirmation will not work, no matter if chip installed or not). Both offer focus to infinity. There is an issue with non fitting screw positions for the 2.8/35 Distagon PC, the 2.8/45 Tessar (AE and MM), the AE 2.8/100 Makro-Planar, the 100-300 mm Vario-Sonnar, the 8.0/500 Mirotar and the Mutar II and III. It's not clear whether it's possible to order a conversion set with appropriate screw holes. At least for the Mutars they do offer M42 conversion sets (as well as for the MM 1.4/35 Distagon and MM 1.4/85 Planar (German/Japanese manufactured with green f/16 position engraving and screws in the mount)).
Leica R: Offers focus to infinity. There are some lenses that interfere with the mirror of the camera. Have a look at the Pebbleplace database for details.
Minolta Rokkor: Offers focus to infinity (without the use of extra glass elements). Seems to be limited to the 1.2/58 Rokkor and 1.4/58 Rokkor. The rear of the f/1.2 will interfere with the mirror of full frame cameras at infinity, so the lens needs physical modification of the rear glass housing. The f/1.4 converts without further trouble.
Nikon G: Offers focus to infinity. Also applicable to the Voigtländer SL II lenses.
Olympus OM: Offers focus to infinity.
Hint: Although not documented on their website, a M42 conversion will enable you to use the same lens on a wider range of cameras with an appropriate adapter (never saw one not fitting tightly there). It seems like Leitax is able to manufacture according to costumer's specifications.