I have been a big fan of Steel for siding for a while now. It is often hard to convince clients to try it. Someday, I hope to use Core-ten Steel on my own house either in flat panel form or 7/8" corrugated sheets. Here is a blog of interest: SIPs House It is a process blog about building a very cool small house in Portland, Oregon. The architects are SEED Architecture Studio. Of particular interest to me is the exterior siding. They Used Core-ten steel panels for part of the exterior. Core-ten is a steel that rusts to form a protective coating. It is very low maintenance and very beautiful. Pricing is unknown - they found a very cheap source. Locally, I have been unable to find it very cheap but I should pursue their link for a potential source. Look around and you may see examples of it in your area. There is a railroad bridge near the exit 3 rotary in Brattleboro made with Core-ten that is beautiful (other than the teenager spray paint thing) Here is a link to the SIPs house blog entry on siding. Also check out how they used old barn boards - beautiful!