There's no guarantee that these web sites are any good, although most of them are, or that they have anything to do with corrugated iron, it's just a some of my own personal favourites.
The Corrugated Iron Club
The website for all enthusiasts

Great Dixter
No corrugated iron but a great garden

The Colonel Stephens Museum
Colonel Stephens was a great user of corrugated iron

Rye Harbour Nature Reserve

Calder Stewart Rooofing, New Zealand

a-matter
A website I like. Architecture and other matters

Angel Design
The brilliant design, illustration and genius art company