On lightness, you'll have to evaluate. But Lift is an approach to web development that is relatively different from most out there, and which I've found tremend

On lightness, you'll have to evaluate. But Lift is an approach to web development that is relatively different from most out there, and which I've found tremendously refreshing, taking some really awesome approaches to separation of content and behavior and other stuff. It also embraces the benefits of static typing throughout and makes real-time stuff stupid easy. You can usually tune how many of Lift's more advanced features you use fairly easily—using it as a simple REST-based server is easy and still extremely pleasant, but going beyond that is also awesome. Disclaimer: I found it so refreshing and awesome that I'm now a Lift committer.