One thing I have loved about PHP is their website documentation. The documentation has a good system of syntax, examples, and related methods (i.e. the substr documentation has links to ereg, trim, word_wrap, etc.). I have loved this as often I am looking up a method to do a task like word wrapping and see that there is already a function to do this. What I love even more is their 'User Contributed Notes' section that allows users to post notes about the method. I have found lots of helpfull code snippets and tips in these comments as well as some of the gotcha's for the methods.

MSDN has now launched a similar service (5 years after php). It can be found at https://connect.microsoft.com/site/sitehome.aspx?siteid=112

It is in beta right now but I would love to see the community help fill out some of those empty sections that I seem to run into once in a while.