Do check out Habu Textiles website if you're looking for fresh inspiration. They have many unusual yarns in subtle color ranges. Unusual in that sense that they are made by stainless steel, paper and copper!
This is how they describe their wool steinless steel yarn: ... the core is stainless steel and wool is wrapped around the core. Because of the stainless steel, there is a memory in the yarn. Create something, twist it around! It will stay in that shape unless you straighten it out.
Doesn't it sound great? I'd love to try this out.