Here's a couple of websites I though some people might find interesting. They simulate different lens effects 'virtually' on a web image..

The first is a page from Nikon that allows you to see the differences between their lenses for a specific scene.

Nikon | Imaging Products | NIKKOR Lenses Simulator

The second is a more general site that shows the effect that different settings of ISO / Shutter /Aperture can have on an image and how it's all a compromise in the end.

Aperture, shutter and ISO value | Camera Simulator