Dynamic URLs via Refinements

[Gordian]

What is the best way to handle large product pages with many different refinement possibilities. Ex. hard drive - 40 gigs - black case  etc. All of these refinements add to the length of the url and potentially create crawling issues as the url is to dynamic.

I have seen people canonical all refinements and pages to the main cat page, I have seen others no follow certain refinements. Also in the SEOmoz crawling report it tells me that over two parameters is bad.

What is the best way to handle this?

Thanks

[RyanKent]

My recommendation would be to place all refinements into a single parameter. You mentioned a 40GB, External hard drive with a black case. How about "40gb-external-black". There is also the possibility of simply using a model number which represents the many choices available.

The question becomes, what is the purpose of adding this information to the URL? Do you want users to be able to read the URL? Or is the need strictly on your end?