From what I've read on numerous websites, the 'Perfect Storm' cocktail is really just a variation of the classic and simple 'Dark & Stormy'. There are many many versions of the Perfect Storm out there, but I like the simplicity of this one. Cut back on the Grand Marnier to 1 oz and you won't notice the difference. You could also sub ginger ale in place of ginger beer, but I've recently discovered that it's just not the same...there is a spiciness and flavour to ginger beer that is so much nicer. Instead of that bottled lime juice, I use a few healthy wedges of fresh lime. Cheers!