Designmeacake.com has crusting buttercream recipes. They also suggest using high ratio shortening which I always do now. Makes the smoothest prettiest finishes on your cake and so much easier to work with! I also use all shortening and no butter. I live in the south where it is hot and humid. My icing just holds up better this way.
Here's one: http://www.cakecentral.com/recipe/6992/indydebis-crisco-based-buttercream-icing
You can use all butter if you prefer. But as cupcakemama said, shortening works best for hot/humid areas, and hi-ratio holds up even better because of the trans-fats. If you want a thick buttercream, don't add so much liquid. To thicken it, add more powdered sugar (10x cane sugar is best). I use it with all butter, but it's always been in air conditioning.
Another good one is Sugarshack's recipe: http://www.cakecentral.com/recipe/5313/sugarshacks-buttercream-icing
I've also found this one good too: http://www.cakecentral.com/recipe/22469/2-icing, but I use only 2 cup of fat (butter) since it's a bit too greasy with 4 cups.
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