About BCL Extensions
BCL Extensions is a small .NET 3.5+ extension method library which contains some handy and sophisticated extension methods for various .NET Base Class Library (BCL) classes. The main purpose of BCL Extensions was to form a central place for us to store our generic extension methods we wrote to avoid clutter in our .NET 3.5+ codebase, namely the LLBLGen Pro v3 designer. We tried to avoid defining an extension method for everything, that's why there's not a tremendous amount of extension methods on a lot of types, just a couple. The main reason is that the more extension methods you define, the more you pollute intellisense dialogs and often you don't need the extension method anyway, or there's a better way to write the functionality.
"Why CodePlex / Mercurial?"
After we decided to release HnD again for LLBLGen Pro v3 as an example project, we looked into which repository sites we could use for this. Before, we hosted the subversion repository ourselves, but nowadays it's not really necessary to host your own repositories anymore. There are really just 5 candidates: Sourceforge, Google Code, Bitbucket, GitHub and CodePlex. I can be short about Sourceforge: not ever will I go back there. Google Code, it's OK, but to me the site feels a bit too simplistic, as if I'm using a v0.1 system. I know most of what you need is there, but one thing feels missing: it's as if you and your project are all alone on a big site.
Read more: Frans Bouma's blog