Anyone know of a font that looks similar to Arial Narrow or Helvetice Neue Condensed, but with a slightly eroded edge? Thanks.

Try these:

4990810 by Phillip Cavette
Alte Haas Grotesk by yann le coroller
Dirty Headline by Cumberland Fontworks
Hotel Coral Essex by Pennyzine
LL Rubber Grotesque by Markus Schröppel
Mal de Ojo by Dynamite Printworks
Silent Hell of Cheryl by SDFonts
Union Agrochem by Polenimschaufenster
Viper Nora by pOPdOG fONTS

or try Grunge-Sans category with close to 50 fonts:
http://www.abstractfonts.com/category/30-48/Grunge