The Banshee is hands down the coolest pub I've ever been to. It's noted as "Scotland's most haunted pub", and boasts two bars, a billiards room, a stage, a cinema, and loads of space to sit down and enjoy a pint (or one of their drink specials, like "The Darkness Within").
Though I was only in Edinburgh for a week, my friend and I managed to go to The Banshee three times, and each time we visited we discovered something new. We didn't even know there was a cinema until our third visit!
If I find myself in Edinburgh again -- and I hope I do -- The Banshee will be one of the first stops on my list.