VDS.Common is a .Net library of useful data structures that was originally developed as part of the dotNetRDF Project. In late 2012 this was split off into a separate project to allow it to be maintained and offered separately.
It offers data structures which include binary trees, tries and efficient dictionaries. Documentation for the library may be found on the project wiki.
Downloads for VDS.Common may be obtained from the BitBucket repository, if you use NuGet you can install directly by searching for VDS.Common in the Package Manager.
Source Code for VDS.Common may be obtained from the BitBucket repository.