As far as bigger companies?
Bell/Textron
L-M (tough to break into, even with connections)
Corning up in Keller (my company) I'd have to check to see what we're needing now... www.corning.com So far I haven't been to great with hooking peole up with jobs however.
Peterbilt up in Denton.
International truck in garland
There's a GM plant too, but I dunno if I'd suggest that right now