I haven't made that many adventurous cupcakes myself - I did a chocolate chip cookie one once, which was basically a vanilla cupcake topped with buttercream with crushed up cookies mixed through it and half a cookie stuck on top. It sounded nice in theory but was a bit too sweet, and that's saying something considering I have a huge sweet tooth.
Last October my mum ordered a box of Halloween cupcakes to be delivered to my flat at uni as a surprise, and they were all really cool. There were all sorts of flavours - ginger and pumpkin, red velvet, chocolate with a white chocolate cream filling (my favourite out of the box), vanilla with purple goo inside...And they were all decorated with really elaborate Halloween decorations. They were so amazing!