First I plan to make it so that the current functionality works without any bugs. :-)
Then I'll basically add whatever the visitors want most.
But first and foremost, I set YAPF up to contain newbie-proof PHP information. All the information in the articles should be self-contained; ie: after reading the article, nobody should have to ask 'yeah, ok, but what do you mean exactly?'
There are tons of 'good' resources out there (like faqts.com) but most of them just contain bits and pieces. You run into a problem, you search, you find the solution, you try again, you run straight into the next problem...
What you really want is a 'complete guide', for ex: an article that will not just tell you how to open a database connection, but also how to retreive data from it, and which are the most common mistakes to watch out for.