I get asked a lot about monitoring "custom" attributes with Orion and while this was definitely possible in Orion v8.x it's dramatically improved in Orion 9.x with the new "Universal Device Poller" or "UnDP".
The UnDP is one of the new features of Orion v9 which released on July 1st of 2008 (about 2 weeks ago). It not only allows you to pull basic data stored within propietary MIBs but also allows you to do some pretty advanced monitoring like pulling in entire tables and running calculations against the collected data.
I've had great success thus far with using the UnDP to collect statistics on static and dynamic VPN tunnels, virtual servers and the hosting infrastructure, fiber switches, multi-battery UPSs, and environmental stats on my Cisco gear.
Anyhow, give it a try and let me know if you think of some cool stuff to use it for.