I just posted some info on the KelTec PF9 in AZGuy's thread...but I'll post it here too.
I have a KelTec PF9 and I carry it all the time either in a IWB or in an ankle holster. It's a great little gun, but the long trigger pull (by some people's standards) takes some getting used to. Contrary to popular conception, it does not have a "heavy" trigger pull, just a looooonnnnng one.
The KelTec PF9 is the smallest, lightest, thinnest 9mm available. Moving up to the P11 (double-stack), you get into the same size range as the Kahr 9mm offerings.
Be cautious if you look on the used market for a KelTec PF9 though. Some of the earlier versions had some feeding problems, especially with hollow point rounds. If you want more information about them than you can read in one day, go to
KTOG Forum - Index and check it out. There is no end of info on there.
Oh, and KelTec's customer service and warranty work are very good.