It's really fascinating to contribute to the FAQ compilation in c.l.php. Once I wanted and compiled few questions and answers, but lost some stuff in poor CD — even I intentionally deleted, as I wasn't convinced about the quality.
The recent compilation work kicked off by John Dunlop and Chung Leong is really evolving. My contribution is now trivial and wishes to contribute more questions—but badly need someone to correct my sluggish English:-( By contributing some questions, I've benefited by readers' feedbacks.
Progress/status bar for file uploading
I'd thought implementing pure PHP progress bar for file uploading (without patch hack or Perl hack) is impossible. But, Chung Leong proved that PHP CLI can be used for the progress bar and hence the pure PHP progress bar is achievable. This is really cool.