[_delirium]

A handful of universities have Research Professor positions. At Carnegie Mellon, it's basically the same as a normal Professor (tenured, similar prestige, etc.), except that you don't normally teach, and in return, you're expected to fund a portion of your own salary out of the grants you bring in. (If you don't bring in grants some year, you can fall back on teaching to earn your keep, so research profs do occasionally teach.)

[pwhelan]

Some of these profs will offer special classes that might otherwise not really get offered or have enough students to warrant forcing someone to teach.

I loved these classes because the profs were usually really passionate about the subject and that showed in their efforts. There was less droning on and emphasis on arcane, irrelevant minutiae and more "basic principles... now we build stuff and talk about the fun problems there". Those classes were so enjoyable that they almost made me pursue a PhD even though I am not right for that -- at least for now.