Tracking "Out of Office" Resources

[Doug]

Is there a way to track resources that are "out of the office".

Specifically, I would like to track resources that will be scheduled to
travel on business so that, on a calendar, I can quickly see resources that
are in and out of the office.

Preferrably, I would also like to differentiate between "out of office" on
vacation and on business.

Any ideas?

Any and all help is appreciated.

Doug