Omar Al Zabir, a Co-Founder of Pageflakes, released his open source ASP .Net Ajax Web Portal.
Dropthings is a open source Web 2.0 Ajax Portal that shows the power of several .NET Framework 3.5 technologies. It supports widget based modularized website, drag and drop personalization of content and an open API for widgets. It is the sample featured in the book, Building a Web 2.0 Portal with ASP.NET 3.5 and you can use it as a personal portal, a group website, a public portal or as a dashboard for an enterprise that aggregates services from different systems.
This is a nice alternative to make your own Netvibes or Pageflakes portal, at no cost.