After talking to people who took handgun courses, it's surprisingly easy to hit a silhouette target with a flashlight coming from it that is extremely bright--it helps them as much as you, it lets them know "he's right THERE."
Night sights first, then lazergrips. Maybe if I had tons of cash laying around, I'd get NVG and an IR light, but until I win the lottery, night sights are gonna have to do it.
EDIT: As for the IDing the target thing....if they're in my house, it's dark, and did something that wakes me up to realize "gee, there's an uninvited guest in my house".....that kinda narrows down the potential options. And besides, there'd be enough ambient light to make out forms (after all, it IS my house, and I know where things are), but not necissarily enough to use regular iron sights. I mean, I dunno about everyone else, but nighttime doesn't equal "total blackness" where I live.