It's pretty popular in web servers. You create a new area per HTTP request, and then everything you need for the context of that request, you allocate from the arena. When the request is done, you free the entire arena.

Nginx does this. As does my Passenger application server.

Apache... kind of does this, but it fakes it. It allocates every object individually, and the "arena" is only used for linking all those allocations together so that Apache can free all of those allocations (individually). facepalm