Krumlink,
In the link I posted to the Ohmite 210 series adjustable power resistors they have up to 10K for 12W, up to 25K for 25W and up to 100K for 50W and above.
Stevez,
My link is to what you are describing, and are available from most large electronics distributors...Newark, Allied,... The windings on some of these are very closely spaced, and with a carbon motor brush for a slide contact can be used for a linear variable pot. I did this many years ago to make the elevation control on a yoke for Microsoft Flight Simulator, with a 100W one, for about 6" or travel.
Mike,
Allied Electronics used to be headquartered in Chicago.
Ken