I've been using Mixpanel, but Woopra looks for powerful out of the box, at least for my needs. I've installed the tracking code and will play with it tomorrow.
OK, I'm on right now, and this kicks ass. This is exactly what I wanted at my last company. When you're dealing with relatively few (but very important) visitors, having this kind of real-time awareness is gold. I can't wait to try it tomorrow when more people are online.