For privacy reasons, I'm searching for an open source album application I can host on my server, Is there such a project? In C#?
I'd like to upload pictures, tag them, have privileges settings etc.
You maybe found what you need with Microsoft WebMatrix.
Composite C1 (directly available in WebMatrix) is an Open Source heavily customizable CMS in C#, that can allow you to use it as an album application.
GalleryServerpro is a pretty good product; I have used it on some sites with very little difficulty and the developer is very good about answering questions if you need help. http://www.galleryserverpro.com