Just curious as to what people are using for metrics in their IGP and what their reasons are; bandwidth? geographical distance? latency?

We have a survey paper on techniques for setting IGP weights http://www.research.att.com/~jrex/papers/ieeecomm02.ps http://www.research.att.com/~jrex/papers/ieeecomm02.pdf and a longer version http://www.research.att.com/~jrex/papers/ieeecomm02.long.ps http://www.research.att.com/~jrex/papers/ieeecomm02.long.pdf that might be of interest. We discuss how to tune the IGP weights in a systematic, automated fashion based on measurement data (of topology and traffic) and an optimization algorithm, and show that good weights settings allow IGPs like OSPF and IS-IS to perform almost as well as optimal routing schemes that have complete flexibility in selecting paths for the traffic. -- Jen