The above example is a gaming clan roster. It shows the basic idea. It will be extremely helpful to have something like this in Xenforo by default. Be it for a gaming roster, a donator roster, a VIP roster, admin roster, staff roster, etc.. Even a "recently banned from thread" roster will be nice.
A roster, in combination with custom user fields, will be something really powerful for those of us who need to in some way or another inform our forum users of who belongs to what group/rank, etc..
The "Members" feature of Xenforo is awesome, but it doesn't quite capture the idea and simplicity of a roster page.
I'm sure many will find this feature useful.