This is a pretty low-tech (and more expensive) solution, but at our wedding reception, we put a disposable camera on each table and encouraged people to just gr

This is a pretty low-tech (and more expensive) solution, but at our wedding reception, we put a disposable camera on each table and encouraged people to just grab them and snap pictures. Afterwards we got them developed, and all of them came with a CD of the pics. This obviously doesn't capture shots taken with other cameras/phones, but is a start.