Extensions for System.Net.Http (especially HttpClient). Provides convenient methods like GetVerified, PostVerified, PostAsJsonVerified and more which take care of error handling for you. Also supports RFC 7807 (Problem Details).
A tool for informative exception handling for sitecore solutions per rendering basis. Documentation, explanation and screenshots are here http://vladimirhil.com/2015/11/15/sitecore-rendering-exceptions-handling. The source code is here: https://github.com/vhil/Helpfulcore
Common .net (C#) code library for dow windows development team. This component wrap the exception handling. Developer can use the interface: ExceptionManager. The component is base on .net 4.5 and log4net.