well, my first project was creating a journal (weblog) script.
or you can do a CMS (content management system) for news and stuff.
the reason i did the journal thingy is because it would have taken care of the common stuff you would be doing in php. Adding, Updating and Deleting records. You will probably end up creating a user management tool tool and also a login/logout script.
another fun thing i've found recently is pick up an old college c++ book a port the c++ classes to php classes. its a learning experience and i had fun doing that. You can alternatively change c++ to java, c, or javascript, asp, etc.....
enjoy.
