Definitely do "lsmod" in the console and make sure you've got usbcore, usb-uhci (I think some distros just call that uhci) and usb-storage up and running - in case one or more of those are not active start them with modprobe.
Once you made sure those three usb-mods work open another console, log in as root and type
tail -s 2 -f /var/log/messages
That will query the message-log of the kernel every two seconds and print any messages going on to the console. Plug in your usb-device and it should show something like "new USB device detected" and the device it's registered as such as (most likely) sda1...
Now all you gotta do is mount it and hooray
PS: Don't forget to add the proper filesystem as argument to the mount-command