Flickr is an online photo-sharing website that is free to use (with more features for paying or "pro" users) that allows a wide variety of people the ability to contribute photos to a personal set or a Web 2.0 collection of pictures viewable by everyone.
Pictures can be limited by Creative Commons licenses or be free use by all or to be totaly private, allowing many ranges of freedom in their service. Often pictures featured on the Davis Wiki are also exhibited on a user's Flickr account as well.
The most Daviscentric aspect of Flickr is the geotagging where users can selectively add meta-data to photos and then view them on a photo map of Davis where pictures are ranked based on "interestingness" (automated activity ranking system). This is very cool for anyone who hasn't seen it. This is where Google Maps got their start entering local pictures (I think, please correct this).
Flickr also operates on a monthly 'upload limit' concept rather than a fixed amount of storage. For free users the monthly upload limit is 25MB worth of photos. $25 gets you a "Pro" account, which means a 2GB/month upload limit and other goodies. Be sure to check out the Davis group.