If you need to do Linux-specific coding and I do mean _specific_, like using libraries or kernel apis that are Linux and not "unix" (e.g. epoll() or inoitify())

If you need to do Linux-specific coding and I do mean _specific_, like using libraries or kernel apis that are Linux and not "unix" (e.g. epoll() or inoitify()) then you will probably want to compare VMWare and Parallels and pick one for your virtualization engine. This will also give you access to windows, which can be useful at times. Otherwise, you will find a Mac to be an very nice BSD box. Get macports and you will have access to just about every open-source project and library you might want. For editing I use Emacs for Erlang, Eclipse/PyDev for python, and Coda for web/javascript. Textmate is also highly regarded, especially in the Ruby community. The only language that you will find yourself lacking will be c# and other CLR variants, but if you really need them you can try Mono or run Windows in VMWare/Parallels. The only other suggestion is less of a Mac tip and more of a coding on a laptop tip: get a more ergonomic keyboard and a larger monitor that you can use at your primary coding desk. It really makes a difference for long coding sessions.