My girlfriend and I both have logins on each other's laptops, so that we can both have our apps set up the way we like them. With bookmarks and history syncing between them, this makes life much easier.
It does, I have multiple logins for my PC including a guest one.
Most people don't seem to really understand the benefit of doing this though, I've seen couples argue because they both keep changing preferences on a shared computer when multiple logins would solve their problems.
