Steal Pippo's ideas and architecture. Because it's awesome. #2
Description
Joking, mostly...
But it's nice that pippo stays very light weight and modular (unlike Spring) and yet still caters to websites as well as web services (where Spark is more oriented toward just services).
It's also great that it has the option of DSL like syntax for defining end points as well as a Controller based approach. And it leaves it up to the developer to pick their flavor.
It's a great overall design I think.