You can also make your own flavor extracts, if you're so inclined. It won't be super-concentrated like this, but it does allow for easy experimenting - you can even make a 5-gallon batch of normal, "neutral" Apelfwein, and experiment bottle-by-bottle once they've conditioned, right before drinking. It's fun!
All you need is a resealable bottle - I use Mickey's grenades, http://www.barefootproximity.com/images/home/mickeys.jpg - and rum/vodka, or even better, Everclear/Grain alcohol. Fill the bottle about halfway with what you want (so far I've only tried spices), and then add the rest vodka/Everclear. I'm interested in trying this soon with baker's chocolate, coffee beans, bananas and perhaps even powered peanut butter. I'll let you know how it goes!