Does anyone have any idea on what to use for "Beer Foam" on a mug of beer? It needs to be able to be a carmel color.

Rice crispies coated in a caramel made up from boiling butter and sugar?
Or use a toffe recipe and after testing in cold water to ensure it will set, add a pinch of bicarbonate of soda, this will make it bubble up, pour immediately into a greased baking ring the size you want the beer "head" to be and it will set with all the bubbles in tact and you have a lovely "honeycombe" toffee layer to die for. Steady on the bicarb though, one teaspoon does for a baking tray size of toffee. Too much will leave a taste, you only need a pinch to get the reaction you need.
Two ideas here, hope someone comes up with some more for you to choose from.

I love the toffee idea. It would taste good too! Thanks!