I noticed I had Photomesa 3.1.2 installed from some time ago and gave it a spin. It's good for reviewing photos - the difference between it and something like Picasa is the seamless zoomable interface. Pity that it has weak knees (it's a .Net 2.0 app) and just dies when it has too many photos to thumbnail or when you get frenetic with zooming. It seems clean enough to install and uninstall, given it's .Net behaviour. Development activity seems to have tailed off.