Flickriver is a nice third party app for Flickr that makes it possible to view images on Flickr as a "seamless river". See for example http://www.flickriver.com/photos/18579464@N03/
The software is not downloadable as such, but can be linked to your Flickr account by way of http://www.flickriver.com/
Yep, I'm using Flickriver very often. The only problem is that it uses a lot of RAM memory when viewing lots of photos, it seems to keep cache of all images in the "river" since the first one so I must re-start the browser