Checkout my project,
mojoPortal, it is an open source web site framework that implements WebParts. Its a starter kit for implementing advanced .NET web sites and WebParts are the most recent feature addition.
You can get the source code free, but to get the latest version that includes WebParts you'll have to use TortoiseSVN the free Subversion client to do anonymous checkout from the Subversion source code repository. Its very easy, instructions are
here, you'll want to get branches/2.1
Hope it helps,
Joe
http://www.joeaudette.comhttp://www.mojoportal.commojoPortal is an Open Source CMS/Portal featuring WebParts and supporting MSSQL, MySQL, PostgreSQL, SQLite, and Firebird Sql