mPaste is a clean, mean and lean pastebinnin' machine.
Syntax highlighting is enabled by default. When viewing "source code" pastes, you can force language hinting by adding a ?pretty= value, for example:
?pretty=
?pretty=lisp
?pretty=r
You can disable highlighting with ?pretty=none.
?pretty=none
Selecting the RAW button () will render the paste in its original content-type.