Online indicator.

[Nocturnia]

As it says. It doesn't have to be that green dot next to the user name, but a status (online/offline) indicator somewhere on the profile or user page would be nice.

[Mahz]

Agreed, I love this feature.

I'm squaring away from performance issues before tacking on a feature like this, but I'm definitely going to get something up.

At least each user's profile can tell you when they made their last post, which is something.