My recommendation would be Microsoft Enterprise Library.
Microsoft Enterprise Library is a collection of reusable software components (application blocks) designed to assist software developers with common enterprise development cross-cutting concerns (such as logging, validation, data access, exception handling, and many others). Application blocks are a type of guidance; they are provided as source code, test cases, and documentation that can be used "as is," extended, or modified by developers to use on complex, enterprise-level line-of-business development projects.
You can get/download the library info from CodePlex (Open Source Community) at
http://entlib.codeplex.com/[
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