I haven't had a kernel panic recently, but if I remember correctly, I used one or both of these options:

Reboot holding Command + S to start in Single User Mode
Type "/sbin/fsck -fy" without "", then hit Return
Once your drive is checked, type "reboot" without "", then hit Return

Reboot holding Command + Option + O = F to start in Open Firmware Mode
Type "reset-nvram" without "", then hit Return
Type "reset-all" without "", then hit Return

You may not need to type at all, depending on your Mac model:
http://support.apple.com/kb/HT1379

Make sure that no application, preference, etc., is causing the panic. Did you install something before the Panic started to occur?

As always, what has worked for some people may not work for all people. Best of luck.