Live PHP syntax checker

+1 live 'any language' syntax check and basic errors would be great actually. For example for Python, running pep8 or pylint and put a sublte bubble with the number of warning (on which you can click to get more infos).

This could be done similar to Build menu. It's simple to create a plugin to run a syntax checker command depending on the file extension/mime (example: php -l) and say ok or not. It might be possible to do it before saving (avoiding you to save a file without being ok).

I would love to have a real-time syntax checker for PHP and Ruby. Pretty please.

Use the Package Manager and install "Sublime Linter".  You can see more info on it here: 

SublimeLinter has an issue with dropbox under OS X, it makes ST2 quit when opening a file that is inside the dropbox folder :(