Undum : A client side framework for hypertext interactive fiction games
choo : A 4kb framework for creating sturdy frontend applications
Pyramid : Pyramid is a very general open source Python web framework.
web.go : web.go is the simplest way to write web applications in the Go programming language. It's ideal for writing simple, performant backend web services.
LÖVE is a framework for making 2D games in the Lua programming language. LÖVE is totally free, and can be used in anything from friendly open-source hobby projects, to evil, closed-source commercial ones.