a neat trick I learned while doing some ajax stuff. set the location.hash property when you want to restore the back buttons.

On my page, before the user leaves the search results to view a detailed page, I set the location.hash to p=## (##= the page number from the search results).

Then when the user clicks the back button, the page they goto is searchresults?id=something#p=9

then on page load in javascript, look for the bookmark, parse it for the p= value, and load up that page of data into the search results.

it's kind of a ugly hack, but it works.