Flickr.com has become more and more popular, and with freeware like Tickr, it is only going to get better.
Tickr is an incredibly fun app. You can search by tag, text or user and then the photos will start to scroll by on either side of your screen or at the bottom. You can also choose the size of the pictures. As they scroll by, you can double click on any of them and it will bring you to the picture on it’s flickr page.
Caution, if you are into photography, this can become very addicting.