Wireless auditing/monitoring rig

[k41zen at live.co.uk (k41zen)]

I was wondering what everyone else were using to audit/monitor wireless enabled devices in a corporate environment
where this is not allowed.

I have a building with three floors and ~900 people in it. I need to be able to identify who the culprit is before I go 
beat them around the head.

Any advice?

k41zen