There are numerous ways to support the PEAR project, that are described in this part of the guide.
There is a chapter devoted to reporting and fixing bugs in the "Reporting Bugs" section of the manual, found here.
If you have a feature you would like to see included in a package, don't hesitate to contact the maintainer of the package. You can find out who the maintainer of a package is by browsing the package list on the PEAR website and selecting the desired package. The maintainer(s) is/are listed on the package information page.
If a developer has given up the maintainership of his package, you can take over this job. If you feel brave enough to answer support questions, fix bugs and manage release cycles, you can contact the previous maintainer or the PEAR developers mailing list and announce your will to maintain the package.
For all the PEAR developers, PEAR is a project they are working on in their free-time, which means that they don't earn any money with it. If you or the company you are working for is using a PEAR package in one of your/their (commercial) products, you/they can do this for free, of course. But if you think that the author of the package you are using desires some credits, it would be nice to buy something from his wishlist at Amazon or another internet store. To see if a PEAR developer has registered his wishlist, surf to the Account information page and select the developer from the list there. If he has a wishlist, it's noted somewhere on the detail page.