There are a couple of different brands of "Clear Bra" that can be applied to the nose end, the most well known of which (at least to me) is by 3M™. They are all fairly expensive @ $500-600+ including installation (highly recommended; self install is tricky if not trained properly), but definitely worth it, IMHO. [Ed: Caveat: I don't have it, but I sure wish I did. :/ ]
As a side note, on the previous generation (2007-2009) Mazda got wise and started putting small strips of the 3M protector on the body at the bottom rear corner of the rear doors so they wouldn't get dinged by rocks and rust like this:
http://www.mazdas247.com/forum/showpost.php?p=3340603&postcount=45
(BTW: never got as far as making the mistake of half-assing the paint repair like I said I would.)
Matter of fact, here's the start of this topic in that thread (since it's relevant):
http://www.mazdas247.com/forum/showpost.php?p=2995120&postcount=33
The factory-applied 3M™ strips seem to be doing their job quite nicely after 2+ years, but then I also don't drive on dirt/gravel if it can be avoided.