Might sound cheesy,but I use a video baby monitor (I don't have kids yet either). The camera with built in mic (which has a built in limiter for when the sound in the live room gets LOUD) sits in my main live room, and the monitor screen/speaker is up in the control room. The screen is fairly large compared to more modern baby monitors. It's only black and white, but it's great because it has night vision so I can still see them if the lights are turned down low in the live room. The camera is also very useful for example if I have someone down there (an assistant or the talent) and I ask them to re-position a mic or something, I can see what they're doing in relation to what I can hear on the studio monitors.
The built in mic is also great because it's good for the artist's talkback mic. I hate setting up a separate talkback mic and channel for it. Also, having the artist talkback into the mic(s) that are recording his/her instrument isn't always doable either (eg a close mic on the guitar amp and the talent is standing 15 feet away). I wanted a talkback mic for the talent to be separate from the console or Pro Tools. So even if I turn everything down to 0 in my DAW for a second, I can still hear a constant feed of the talent's talkback. To talk to them in their headphones from the control room, I use the built in talk back mic on my Mackie Big Knob. It's omni directional and has a good amount of gain on it's pot, so anyone in the control room, no matter how far from the Big Knob, can talk back to the talent as well (if I am holding don the button).
But they can't see me! It's kinda Big Brother-ish I know, but hey, that's the world we live in today anyways! Besides, why do they need to see me biting my fingers in anticipation that they finally get the right take the 100th time when the pressure is on?!
Edit: The video latency is pretty much non-existant so it's great for someone recording something in the control room and seeing the drummer simultaneously recording down in the live room.