Couple of ideas

Chat room using Java for instant messaging.

Also, in addition to the real time reading. Funadvice could get a people count for each person in each category so we can see how many people are reading or browsing that group.

Travel (102)
Health...

(56)
Games (242)

And so on. The numbers could represent the number of people in that category.

Good ideas, actually...we have something in mind, expanding on our spy feature, that would show on the category page what questions were being read, in real time...not by who though

And yes, a chat room has been on our to do list for a long time (well, ever since we removed the chat facility nearly two years ago)...problem is, with the growth we've had, it's been harder and harder to get stuff out the door, as it takes longer at scale.