I was wondering if it would be at all possible to have a login required before loading the drivers. With a few exceptions of course. I'd make the passwd and shadow files on it's own small partition with a very strange filesystem, like hpfs or something i'd never use. Have the kernel load that, then ask for a login. If authenticated then go on to load the rest of the drivers (ext3, scsi, network cards...). This I think might significantly increase security. Not that it is necessary of course. I've also been playing with the idea of securing the boot loader somehow.
Any ideas of how to implement this?