You might want to ready my answer to this question on Quora: http://www.quora.com/If-I-have-a-website-with-millions-of-unique-pages-should-I-submit-a-partial-si

You might want to ready my answer to this question on Quora: http://www.quora.com/If-I-have-a-website-with-millions-of-unique-pages-should-I-submit-a-partial-sitemap-to-Google http://www.quora.com/If-I-have-a-website-with-millions-of-un... Where I explain how we did this at eBay when I was working there. eBay is quite unique from the fact that millions of new URL's get created on a daily basis, with a short lifespan.