These are the ones I’m aware of:
-ms-
Microsoftmso-
Microsoft Office-moz-
Mozilla Foundation (Gecko-based browsers)-o-
,-xv-
Opera Software-atsc-
Advanced Television Standards Committee-wap-
The WAP Forum-webkit-
Safari, Chrome (and other WebKit-based browsers)-khtml-
,-konq-
Konqueror browser-apple-
Webkit supports properties using the -apple- prefixes as wellprince-
YesLogic-ah-
Antenna House-hp-
Hewlett Packard-ro-
Real Objects-rim-
Research In Motion-tc-
Tall Components
These are officially listed in the CSS 2.1 Specification, informative section 4.1.2.2.