Recently I got Brit hooked on Flickr and it only took her 3 days to hit her monthly bandwidth quota. However, what's more interesting is that I needed to find a very intuitive application for her to edit photos quickly. And those of you who know me, I'm all big into thin clients, so I started googling.
I came across one called Picnik and holy cow is it awesomely simple / powerful. I've caught myself using it to resize and crop photos rather than pulling them into The Gimp. And it integrates easily into Flickr or Picasa.
A very neat find, especially for minor picture changes.