I have done quite a lot of work with Flickr. I am (at least at work) primarily a .Net developer so I wondered how hard it would be to create a wrapper library for Flickr in .Net.
First off, I looked around the internet for suitable libraries that already existed. There was one being run on the GotDotNet website that contained some code for uploading a photo, but nothing for general API calls.
Anyway, to cut a long story short I developed most of my API calls, then merged with the other .Net development team to create what is now the Flickr.Net API Library. [View Development Website](http://www.codeplex.com/FlickrNet "Flickr.Net Web Site").
The first application I wrote to use the Flickr.Net library was the Flickr.Net Screensaver, a windows screensaver. For more details see the [Flickr.Net Screensaver Page](/flickr/flickr-screensaver).
A list of applications using the Flickr.Net library can be found over at [CodePlex](http://www.codeplex.com/FlickrNet/Wiki/View.aspx?title=Applications&referringTitle=Home).