Flickr is a shell of what it used to be; Instagram makes everyone's pictures look the same and Picasa isn't really ideal for browsing great pictures taken by a great community. 500px, on the other hand, seems to only have great pictures. Their iPad app is an extremely elegant way to browse them.
500px is like Flickr, if Flickr filtered all the crappy photos that the bulk of their users sometimes post and distilled it into true art photography. So it's a place where really good photographers can store their pictures in polished portfolios for other really good photographers (or just other people) to see them. It's an elite social network for photogs, basically. The iPad app is an extension of their web site, you can browse popular pictures, see editors picks, new pictures, your pictures, your friends pictures and your favorites too. It's dead easy to use, just click what you want on the left sidebar and swipe away for more pictures. The thumbs can be enlarged and zoomed in to get a clearer view.
It's like having a never ending source of pictures to browse through. You can share your favorite pcitures on Twitter, Facebook and Tumblr or e-mail them and open the picture in Safari. The app is especially good at removing you from reality. Having a bad day? Fire up 500px and swipe through the pictures and see the world's beauty. Want to get better as a photographer? Crib off ideas from the professionals. Just want a new wallpaper? Take a screenshot. 500px feels like an exclusive club, where everyone knows how to take pictures, that you can have access to on your iPad, even if you don't know your way around a camera. I do wish there was a search option though. Oh and for parentals and the prudish, you have the option to turn off nude pictures too.
500px is a free download from the App Store, for the iPad