Flickr is a popular photo sharing and hosting service owned by Yahoo. It supports an active and engaged community where people share and explore each other's photos. You can share and host hundreds of your own pictures on Flickr without paying a dime. There's also a pro service that gets you unlimited storage and sharing for about $2 a month.
Besides sharing your photos, Flickr supports HD video. Unlike other sharing sites though, users videos are capped to about a minute, which the creators hope will create a whole new genre of videography that's a little more like a long-form photo.
Both photos and videos can be accessed in Flickr's API, which has led to some interesting third-party mash-ups. It's also made for some neat ways to integrate Flickr shots into blogs and social-networking profiles.