There are tons of 'butter creams'.
American is a very sweet thick concoction of icing sugar, butter and a small amount of liquid.
Then you have meringue bases, Swiss meringue and Italian meringue. Italian, in my experience, is a bit firmer, sets up a little better and is better to pipe with.
Then there's french butter cream, by far my favourite, it uses egg yolks instead of whites. It's a very silky buttery frosting, denser than the meringues ones. It isn't the greatest for piping details, but I use it on cupcakes all the time.
There is also roux butter cream, where you cook milk, flour and vanilla into a paste, then beat it with granulated sugar and butter, it's also delicious. (It's called a few things, heritage frosting, fake buttercream, cloud frosting)
I use a real vanilla bean or bean paste, and it comes out tasting like room temperature ice cream, lol. You just have to beat it for a long time to get it smooth and fluffy. It doesn't hold up to heat very well though.
Personally, I never use shortening, can't call something without butter 'butter cream' :) I also don't live in a very hot climate though.
If you are worried about that, you can sub in some high ratio shortening, or try out http://cakecentral.com/a/indydebis-crisco-based-buttercream-icing
I've never used it, but I've read good things about it on CC.
Edited by scrumdiddlycakes - 4/7/13 at 1:52pm