I feel certain that an entire generation of careers started from Rasmus Lerdorf's little hobby project. Despite the fact that things like Perl Mason, Tcl web apps, and your bog standard CGI scripts already existed, nothing compared to PHP's wild grab bag of a standard library, and above all, the documentation with user-contributed notes and examples (not to mention that there was nothing similar/free in Windows-land).

In some ways, that incredible ease of use of PHP for backend mirrored the ease of use of Macromedia Flash for animators and front-end/UX designers, which also led to a generation of middle schoolers and high schoolers tinkering and learning from each other and accidentally falling into a real career path.

Thank you Rasmus and PHP team... despite all the warts PHP gets often-deserved flack for, you have undoubtedly changed the lives of, quite possibly, hundreds of thousands of people who would never have become professional developers without the easy on-ramp that your creation provided.