At XL when we have run into this issue, we have used; http://www.techland.co.uk/index/kvm_av400 with the long view option for remote monitoring of single output servers.

This also looks interesting for dual output servers; http://www.rose.com/htm/multivideo.htm when used in conjunction with http://www.rose.com/htm/crystalviewplus.htm

Cheers,

Phil