The industrial side spans many crossover genres, in fact I don't think you could say there is a definitive industrial sound. For me it's along the lines of FLA, as that's what I started out with, most will point you to Skinny Puppy. Note: most of the bands are extremely prolific, have many side-projects, and their discography covers a couple of decades, so there will be lots of variation.
Some industrial stuff to check out that I am familiar with.
Skinny Puppy/Download, Front Line Assembly, Velvet Acid Christ, Die Krupps, Nine Inch Nails, Rammstein, Sielwolf. For a darker, less aggressive sound, try early Delerium, Synaesthesia, Xorcist.
http://www.industrialmusic.com/
http://kzsu.stanford.edu/eklein/
http://www.metropolis-records.com/ I think ANYTHING released on Metropolis will put you in the genre.
Metal covers as much spectrum as industrial, if not more, as it's more 'rock' than industrial is, so there is tons more cross-overs and leakage to the mainstream. (Mainstream music is getting harder overall, and this pleases many people
On one end (or corner) for example, it blends into industrial with such acts like Fear Factory and Ministry. I've been out of this scene for a while, but a friend of mine used to run an online zine for a few years, here is the links page:
http://disemia.com/creation/links/