I came across this pretty cool feature on firefox 3.6. It helps to delete a single website you have visited. The difference here is that, in the previous versions, you couldn’t delete a particular website/domain you have visited. This used to be pretty annoying but with this feature you can do it. Here’s how you do it:
1) Goto History
2) Show all history
3) Click on a particular site you have visited
4) Right click and then select forget about this site.
5) This will delete all the history you have stored on that computer, for a single website or domain name only.