Supplemental hell

After reading John Chow's post about getting out of the Google supplemental index, and then reading that Shoemoney has managed to increase his traffic by a staggering 1400%, again by getting out of Google Supplemental, I had a look at the supplemental index for the site I work on for my day job. It doesnt look nice, with around 265,000 pages in supplemental.

Why is this important?
In the words of one commenter on Shoemoney:
"Removing duplicate content and pages with little to no written content bring a lot of pages out of supplemental. The more pages your site has in supplemental the less ranking power your domain has. If you decrease your supplemental pages your domain’s pagerank and ranking power increase."

I'd better get working on this one so. Thankfully, Google has made it easier to tackle this, as Googlebot recognises wildcards in your robots.txt file

e.g.

User-agent: Googlebot
Disallow: /*sort=

will stop Googlebot indexing ANY url with the string "sort=" in it.