NAMI Warm Line: 1-877-535-4357. Whoops, that was a number more local to me.
Try: (800) 950-6264
They are a good general resource:
http://nami.org
It's interesting to me in how you describe these thoughts. In the past, almost the same exact thought would pop into my head, almost casually yet always by surprise. Like, "I could fix a sandwich, or see what's on TV, or I could always just kill myself." As if it were a casual, everyday kind of thought!