I'm using MSYS http://mingw.org/wiki/msys heavily, it has bash and all file and text processing utils. It's also distributed as a part of Git port http://msysgit.googlecode.com.

Lots of other utils can be also found in GnuWin32 http://gnuwin32.sourceforge.net/packages.html.

Btw, the sed in Gow would deserve update from 3.0.2 ;) https://github.com/bmatzelle/gow/wiki/executables_list