SiteMesh - We’re kicking off a new project from scratch at work and that’s always a good time to read up on some of those projects you’ve heard mentioned on blogs or lists. Short version: SiteMesh met all my criteria for adoption with excellent intro docs and clear installation instructions.
There are a few fairly superficial criteria I use to judge whether something will be useful or not:
I haven't put into algorithm the exact process I use these criteria to judge projects, but they're always there. Sometimes a fantastic install will outweigh other factors, sometimes if someone I really respect uses a project I'll cut some slack elsewhere because I know the result will be worth my time.
So that's a long-winded way of saying that SiteMesh succeeds on all fronts. The introduction is on the home page and very straightforward. And on the right-hand side you have an Installation and Configuration link which shows you how to get started in about ten minutes, showing you code and configuration and telling you where to put it. (Fifteen for me because there were some very minor changes necessary to use it under Tomcat 5 and the 1.4 webapp spec. But still easy.)
Well done SiteMesh folks!