Aspect# is an AOP (Aspect Oriented Programming) framework for .NET. It
uses Dynamic Proxies and XML configuration files as its basis and is
compliant with AopAlliance.
Byldan is a framework for managing the build
lifecycle of .NET applications. Its goal is to
support multiple platforms (Linux/Windows) and
multiple compiler vendors (Novell/Microsoft).
BOAPI is an implementation of default often used business objects in different programming languages with an identical public interface. It supports PHP 5.3 (with namespaces), C# (.NET port), and Java.
OpenDMS.NET lets you implement a document management system into a project of your own or as a stand-alone DMS. The API is based on HTTP, so clients are fairly straightforward to develop.
The OpenGamma Platform is a unified system for front-office and risk calculations for financial services firms. It combines data management, a declarative calculation engine, and analytics in a single comprehensive solution.