It seems most people use buttercream for the binder in cake balls but I'm wondering if anyone uses anything different. Coffee flavors, different types of icing? anything?
Liqueur is wonderful as a binder.
at the bakery I worked for we only used cake. We compressed it and kneaded it until it was like a cookie dough. Made it less sweet but very rich
Carmijok, I second that too. If you use an icing, I prefer a bare minimum for taste.