I think it would be a good idea to have the ability to show all entries that share the same password.
After I started using 1Password I usually created a unique password per login. Unfortunately most of the logins I created before share a couple of passwords.
With the recent incidents (stolen passwords on linkedin, eharmony, ...) in mind I think it's a good idea to get all accounts which share the same password.
And it would be great if there would be an option to have something like an exclamation mark next to the entries with duplicate passwords in the browser plugin. With that I could see directly that I should change the password when I log in to that site.