Open Source Web Application Framework for the Microsoft ASP.NET platform.
Full-featured, fully customizable, multilingual, skinable, multi-document web based WYSIWYG HTML editor control. Microsoft Internet Explorer, Gecko based browsers (Firefox, Netscape, Mozilla) and Opera 9 are supported.
Free and easy-to-use webmail script with AJAX interface. Supports POP3/IMAP accounts, SMTP, SSL. Users can check and send mail, use address book. Skins, non-English languages, UTF-8. MS SQL/MySQL/MS Access backends supported.
An ASP.NET forum module which is supposed to work on Mono and .NET with MySQL, MS SQL, PostgreSQL and Firebird databases and written on c#.