If you use Firefox, which you should, then I recommend trying the PicLens plugin. I discovered it a few months ago, but didn’t install it until today because of the stability issues of Firefox when you have a bunch of plugins running. It’s a really cool way to look at pictures on the web and works on most picture sites (Flickr, picasa, photobucket) as well as Facebook…and more! Anyway, check it out, then head over to Flickr and pick a group to browse (my Flickr name is Johnny Boy! if you want to see my pics) and click the arrow that appears when you hover over a photo. You won’t be disappointed.
A side note….I’ve used the other plugin from this same company called CoolIris Preview, but it wasn’t very useful. I ended up bringing up pages accidentally and it takes just as long to load a preview than it would to actually load the page, so it doesn’t buy you much.