I think you can find a "sugar free" chocolate powder mix. The same stuff you add to milk to get chocolate milk.

vailla beans. they are expensive but zero cal. Just cut open the beans and then scrape the insides. or you can try natural extract. they have it at trader joe's, no alcohol or sugar.

I mix mine with apple juice post workout---

http://www.ast-ss.com/articles/article.asp?aid=77

To immediately shift metabolic mechanisms toward muscle recovery and growth, your first priority after training should be to get blood glucose and insulin levels up quickly(2). To do this, consume a dose of simple, easily digested liquid carbohydrates after training (around 0.5 of a gram per kilogram of body weight).

Other times I mix with good ole peanut butter---

bgodd1, fructose is not an ideal carb choice post workout,it replinshes liver glycogen before muscle tissues. dextrose and/or maltodextrin would be optimal.

ball22, perhaps try adding Crystal Light, different flavours. Or sugar free fat free pudding mix powder.

You can add an extract like vanilla or hazelnut to add some flavor.
If it has no sweetener in it either, you may want to add a couple of teaspoons of splenda and then add the vanilla extract.