Assuming that you are serious about being a software developer, you really should make a conscious effort to further your skills. The shelf life of technical skills is growing ever shorter, and no effort put forth in keeping up-to-date in trends and developments can be considered wasted.
But how should you spend your precious time? You can't possibly learn everything about everything, and well-rounded technical individuals are considered quite valuable commodities.
PHP is more than the details of session management, file-downloads, and configuration variables. PHP is a language that grows and changes over time to suit the needs of developers like you who need to have it done by yesterday.
Although the design and implementation of PHP is geared toward Web site development, PHP can be used for more than interacting with a browser. Consider what you can do if you have a tool that had the ability to run seamlessly across Windows and Linux as well as communicate with file systems and nearly every popular database. What else can you do with it? How about:
Gather RSS/Atom feeds
Test forms/sites from alternate Web development technologies
Use Perl-like text processing
Run generic utilities
Even if you don't create Web sites every day, you can still find opportunities to leverage your hard-earned and valuable PHP skills.
Yes, these are also known as the dreaded "people skills.'' Even PHP geeks need to interact with real physical people, even if they are other PHP geeks. Plus, not all code is considered equal, and unused code is even considered a liability, so scoping your problem and creating the right product is paramount for success.
Predictably, these abilities are not thought of as standard technical skills, even though you may spend a significant amount of time interacting with clients and co-workers; even though an unsuccessful project may threaten your project, company, and very livelihood; and even though months of work might be wasted solving the wrong problem or adding useless features.
Time invested in enhancing your nontechnical technical skills goes far. You may consider beefing up your agile development techniques, such as in those used in eXtreme Programming. Lessons can be learned about how not to write software, so knowing at least a bit of how previously popular development methodologies work will help your understanding of where you are going.
Writing software isn't exactly magic, and more of what was considered art is slowly falling into the category labeled science. Here are a few resources that are academic in nature yet offer a short-term payback.
Well-written, concise code will tend to have a high degree of design patterns even if unintentional. Design Patterns by Gamma, Helm, Johnson, and Vlissides (Addison-Wesley) is a classic and comes in easy-to-swallow chapters. Learning just one per week will make half a year fly by in no time. With Writing Compilers and Interpreters by Ronald Mak (Wiley), knowing how PHP and similar languages do their magic goes a long way when the going gets tough. Refactoring (Addison-Wesley) by Martin Fowler examines the techniques for achieving well-written concise code. Agile Modeling: Effective Practices for eXtreme Programming and the Unified Process by Scott Ambler (Wiley) goes into detail regarding the integration of agile development practices and standard modeling techniques.
PHP exists because it was developed as a community effort. Scores of developers have been involved in the process, even if in the capacity of testing, which, by the way, should probably carry more weight as they seriously influence the development process.
The day will arrive when you find when a PHP utility or application that needs to be repaired, or someone might offer a patch for something that you wrote. Either way, a dose of humility goes a great distance in the political process, and this is no exception because a reputation for being foul-mouthed and short-tempered will not help any project.
On the other hand, actively contributing to community projects such as PEAR increases your personal PHP skills, and the value of the effort is multiplied by the time saved by similar developers using your tools. Even if you're not as technically astute as the project may initially require, the act of creating a How-To or developer-targeted tutorial is often a great help in learning a new technology. Unfortunately, good documentation is often lacking in the best of projects.