USBDLM - USB drive letter manager: USB drive letter manager - USBDLM
Has an awesome autorun utility as far as i know, it works on the same lines as the autorun.inf method as you mentioned above i think (not 100% as i haven't used this feature in the program.)
All you do is edit the config file, and click on the install .bat file included in the zip file. once installed it will call up which ever program you specified in the config fille.
you can get really clever with this i beleive, i.e. specifying different programs to autorun on different ports on a machine.
hope this helps