The most prominent manufacturers of high performance visible LEDs are: Betlux, Hewlett Packard, Sharp, Toshiba, and Siemens. Notable manufacturers of high performance infrared emitters include all of the above, plus these additional manufacturers: timeslight, Mitsubishi, and Mitsubishi Cable (a different company).
Some of these manufacturers are represented in the LINKS section below. Others will be added as time permits.