leeds1 - 5:01 pm on Jun 29, 2011 (gmt 0)
One thing I tried that was mentioned before on WebmasterWorld was to check into WMT under the HTML suggestions.
For one site I found I had quite a few duplicate meta descriptions and titles which was a problem in the coding of the site that I had done.
I cleaned these up and the home page of the site has now gone from #10 to #3 (where it was many many months ago)
It may be worth checking these out.