Some advice please. I've a popular site (usual story, keen hobby that generates some Google Dollars).

I want to develop it by allowing users to register, select their own password, which allows them access to a series of pages. Can anyone recommend a source for this code/software? There's a lot around, but what works best for you?

In the future I wish to add some forums, and maybe charge for content (PayPal).

Thanks to you all.