Eclipse is an IDE of choice for many. It's been very popular among Java developers for a long time, but lately it is getting some traction in the PHP world, as well. A big contributor has been the absolutely fabulous Eclipse PDT project that makes Eclipse PHP-intelligent.
Whether you are developing in Java, PHP or any other language Eclipse supports, you most probably have to deal with cross-platform issues. One of the most trivial, yet annoying is the matter of line-delimiters. For whatever historical reasons Windows, Unix/Linux and Macintosh use different delimiters. It almost makes you wonder if the creators of the three major operating systems were sadistic enough to intentionally employ all three possible variations to make our lives more difficult.