I think you could use this horse mold from First Impressions, mold them in white chocolate and make the spiraled horn of fondant or gumpaste. The size should be just about perfect for cupcakes.
http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=526513
http://www.firstimpressionsmolds.com/index.asp?PageAction=VIEWPROD&ProdID=2502
My daughter wants dolphin cupcakes for her party at school and I usually just ice my cupcakes with a 1M tip then add a chocolate transfer image to each cupcake. In this case, I will be making dolphins out candy melts to place on top of each cupcake...an idea if you were looking for an alternative???
Schmoop and Kim_m_kk
I think I can help both of you at the same time. I found these lovely flexible molds in the the clay isle of the craft store and I think they will be perfect for you.
Here is the link so you can see what I am talking about.
The one with the unicorn(I love unicorns) is called Fairytale-did not see it on this page but just bought it yesterday
http://www.sculpey.com/Products/products_eztheme.htm
Hope this helps
Dayana 
There is this cupcake http://jas.familyfun.go.com/recipefinder/display?id=50217 or I shrank a coloring page of a unicorn made chocolate transfers to stick ontop of my daughter's cupcakes. I don't have the picture on here yet though. I did the outlines in milk chocolate, let it set and then filled it in with white chocolate.
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