I use xfce as my wm/desktop. Here is how I got my usb stick working:
1. (as root, so you'll have to use sudo) mkdir /mnt/key.
2. I added the following line to my /etc/fstab file. Again, you'll have to do as root, (sudo gedit /etc/fstab)
/dev/sda1 /mnt/key vfat noauto,user,rw 0 0
3. Then, in xffm, under the fstab widget, you'll see /mnt/key, plug in your usb stick, right click on /mnt/key and select "mount". Your files will then show up.
After you're done, you'll have to right click on /mnt/key and select unmount. Anytime you use it in the future, simply repeat this last step.
This is the manual way to do things, though. I prefer to manually mount and unmount my media, so it works for me. You might want to check out ivman
. For something that will work automatically. I don't know if it is in the ubuntu repositories, but it is worth a look.