Looks to have lots of info that could help you out. I think that you can probably get ntc thermistors with a variety of temperature coefficients. Check out their product listings.
There was a very good multi-part article written on NTC (negative temperature coefficient) thermistors in http://www.sensorsmag.com/articles/0597/negtemp/index.htm magazine online[/i]. Perhaps you can find some useful information there too.