GH2 with Snapseed
Following up a recommendation in this forum I bought a copy of Snapseed http://www.snapseed.com/
It's very simple to use and many of my recent shots on the GH2 really seem to benefit (at least for web viewing), e.g:
Some of the filters tend to exaggerate the noise a bit (most of the shots were taken at ISO 160 or 640), but for most usage this is not an issue.
I wish Snapseed had a few more styles and options, especially for frames (maybe it will grow) but for simple and quick enhancement it seems great.