TeamCity by JetBrains --> Free Professional Edition

Free Professional Edition
Get a freeware continuous integration server with lots of possibilities for delivering high-quality software.
http://www.jetbrains.com/teamcity/

Continues Integration

Continues Integration Factory
http://www.cifactory.org/


CruiseControl.NET is an Automated Continuous Integration server, implemented using the Microsoft .NET Framework.
ccnet.thoughtworks.com