Access either via Java classes or prehaps GetMetricData() to all active sessions and applications. This would be similar to Adobe ColdFusions undocumented coldfusion.runtime.SessionTracker and ApplicationScopeTracker, which allow access to other sessions, application scopes and information like time alive, idle timeout, idle time and expired state (before collection).
This could be the basis for an admin section for monitoring applications and sessions. Developers could also use this information when creating their applications (user sessions for an app, who's online, inactive sessions etc...).
We’re investigating this for a client so it may appear as an extension at some point.