I built a bunch of custom figures out of Kreo and hope this sub-forum is the proper place to brag about them. They don't transform, since there aren't nearly enough joints in a Kreo kit to make a transforming figure, but they do look spiffy. Pics are at
https://picasaweb.google.com/109663474567694169051/Kreo?authuser=0&authkey=Gv1sRgCL7e-f-zlqi8iAE&feat=directlink.
Cheetor (yellow cheetah): Made entirely from pieces from the Bumblebee kit, and probably my favorite creation. Awesome range of poseability, looks decently like a cheetah despite being made of car parts. And he can sort of eat kreons!
"Grimlock" (gray velociraptor): It looks better than the actual Megatron kit. How can you call a robot with dumpy shoulders, a rectangle for a body, and no BFG a "Megatron?" Now he's a dinosaur, and dinosaurs are always cool.
Fracture: I wanted to build a fembot, possibly Elita-1. Unfortunately, transformers that are made of legos aren't that curvy, so while she does have a reasonably feminine figure, her shoulders are a little too broad and the waist is pretty boxy. Since she has the really wide head of Crasher the Go-Bot, I think she's a better fit for Fracture/Crasher than Elita-1. While I think she uses the "decorative" blocks better than the Sideswipe kit from which she was derived, I feel I could have done much better.
Enjoy.