Recipes please? Im not very creative when it comes to these things!
AYou can use any fillings like you would for any other cake. Buttercream variations; Vanilla Bean, Coffee/Mocha, Chocolate, Berries, Cookies and Cream, etc. Ganache; Dark, White, Milk-you can get creative flavoring ganache as well-White Chocolate Peppermint, Caramel, Chai, etc.
I like to mix flavors, White or Dark Chocolate and Raspberry (or strawberry) Mudcake, Caramel, etc.
Think of drink combos that you like, candy, ice cream, desserts...
Once you master your basic recipes you can start playing with flavor variations, that goes with any cake, filling, or frosting.
Cherries go really well.