If you intend to cut new nuts from blanks and/or intend to do a lot of adjustments then a top quality, pro set of files is a good investment.
I bought a set of "Noman" files on ebay.
http://cgi.ebay.com/Norman-Guitar-Nu...d=p3286.c0.m14
These are not the right tool if you intend to do a lot of nut work. It seems the steel tends to dull a bit to quickly. However, for the occcasional adjustment they work great. I've also heard good things about the feeler gauge, welding tip cleaner strategy. For the occasional adjustment, I'm sure they will work fine.
"The music business is a cruel and shallow money trench, a long plastic
hallway where thieves and pimps run free, and good men die like dogs.
There's also a negative side."
--Hunter S. Thompson
Guitars: Dean Sweet Wood 00R, Martin D2R, Guild D60, Guild D35NT, Morgan Monroe M30, OS baritone Uke