If you want to be absolutely sure that you didn’t miss a new type, property or method inside the .NET 4.0 framework, have a look at the following links. They provide a comprehensive list of the new namespaces, types, and members in the .NET Framework version 4 and provide links to the corresponding reference topics.
As a developer there are a lot of small tasks you need to do as part of your coding, debugging and testing activities. DevToys is an offline windows app that tries to help you with these tasks. Instead of using different websites you get a fully offline experience offering help for a large list of tasks. Many tools are available. Here is the current list: Converters JSON <> YAML Timestamp Number Base Cron Parser Encoders / Decoders HTML URL Base64 Text & Image GZip JWT Decoder Formatters JSON SQL XML Generators Hash (MD5, SHA1, SHA256, SHA512) UUID 1 and 4 Lorem Ipsum Checksum Text Escape / Unescape Inspector & Case Converter Regex Tester Text Comparer XML Validator Markdown Preview Graphic Color B