PL/PGSQL Cook Book

I've just spent the last day or two trying to get to grips with plpgsql and can't believe how abysmal the documetentation and examples are.
I've been trawling through the mailist lists and I notice there was talk back in 1999 abouta PLPGSQL Cook Book - did anything come of this?

If no one is maintaining something like this and people think its a good idea I think we should have another crack at it.
I'd be happy to maintain something like this and put it up on the web, although I'm only a newbie and would rely upon user contribution.

Here are some possible sections to help get people thinking. Even if you don't know the answer send me the questions and I'll add them to the list.
How can I create Tree structures?
Are recursive functions supported?
Whats are the advanteds disadvantes of the different scipting langues PL/PGSQL, PL/Perl, PL/Tcl?
How do variable scopes work in PL/PGSQL?
Can I output variables from a function to the command line for debugging purposes?
How to debug PL/PGSQL?
Various examples for each of the statements

Anyway lets discuss this, a lot could be done just from piecing together relavent tips from this mailing list.
ie there are some good posts on tree structures, which if I'm willing to piece together if people think this project is worth while.

Regards

Mark