I recently flipped Madame's car seat from rear-facing to front-facing, and one of the benefits (besides the fact that her feet aren't cramped up against the back seat) is that I can see her in the rear view mirror. Sort of. Actually I have to move the mirror to see her, and then move it back to see the cars behind me, which isn't very safe.
Yesterday a MDD reader pointed me to a post he wrote on TransportTrends.com about a new high-tech rear view mirror. It's got a little 4 inch LCD monitor so you can see not only what's in the mirror, but also whatever you've got a camera in your car pointed at. I think the original idea was to use the camera for blind spots (particularly directly behind/under your vehicle), but TransportTrends suggests pointing the camera at the kids behind you. It's an interesting idea, though at almost $500 for the mirror/monitor alone, you better be putting it in your brand new Hummer. I think I'm going to try the little attachment mirror we got a year ago at the baby shower first.
Clip on rear view mirror with LCD color monitor. [TransportTrends.com]