I love using Delicious and share the same PC as my girlfriend. When my she logs into her Yahoo! email account, I need to log out of my Delicious account because its tied to my Yahoo! login.

So because of that, I can't use Delicious as a social bookmarking service.

I love all its features and need an alternative that also uses Firefox addon integration and tagging.

I've tried diigo.com but tagging is annoying. You can store your URL under your own tags but you don't have a clear way to later browse your tags in the Firefox addon. (The delicious approach is way much better and simple).

Any suggestion of any service?