We have recently launched a code sharing community web site called MSDN Code Gallery.
MSDN Code Gallery hosts code snippets and entire projects that have been shared with the community. You can publish your own code or search for and download other peoples' code.
There are lots of nice features on the web site. For example, when you publish code, the site enables issue tracking, discussions, comments and RSS feeds pertaining to your release.
The basic format is that you create resource pages. These pages each have descriptions, versioning etc. and contain releases. Each release is a file. It can be a code snippet or documentation or any other useful file. You search the gallery using tags or using the embedded Live search. Also, the web site automatically enforces the Microsoft Public License on all the source code downloads.
All in all, it seems like a great idea, so, I'll be publishing all my source code to the MSDN Code Gallery.
If you're interested in publishing your own code, you can find out how to do it here.
As an example, the resource page for my post on filtering a PivotTable using cell contents has been published here. The workbook can be downloaded from the Releases tab.