My Navigon 2100 comes with Mobile Navigator 6 preinstalled. Like MioMap 3.3, you can change the skin of it. The file is in MN6 directory and it’s called MN6ResourcesBinary.res . There is an active thread discussing the skin for Navigon 2100 on GpsPasSion.com. If you have time, you can read through the 100+ pages of discussion. There is another thread dedicated to just the finished skins. This is where I got the skins for my package. You can download more skins from this thread.
I modified a script that does skin switching for MioMap 3.3 to work with Mobile Navigator 6. Therefore, you can switch the skin from within Navigon 2100. You can find the script in my Navigon unlock package. The script is called tweaks.mscr in the Script directory on the storage card. If you want to add more skins, just create a separate directory for each skin under Skins directory and put the MN6ResourcesBinary.res file in that directory.
Here are the screenshots of the skins I included in release 4.2.
350Z by BLUE
Mini Cooper by josephgullett
L0st3 by L0stS0ul
Superman by cajnape