Windows 7 crashed during bootcamp install. Now the option boot-up does not work. When I turn the imac on it ignores all option commands and goes to no bootable device -- insert boot disk and press any key.
The install likely damaged the boot partition, making the Mac think there are no operating systems at all. It is likely/possible that your Mac partition is OK.
Can you boot with COMMAND-R (recovery mode) and reinstall Mac OS? That should fix the boot partition and get you back up and running.
Doing so should not cause you to lose any data as long as you don't reformat the Mac OS partition. But you did make a backup first. right?