DotNetXtensions.Common2 (nuget): A number of helpful types and extension methods:  A DropOffStack, binary-search members (on virtual collections, not just on an array), a GridOutputBuilder (for simply outputting lines of output in aligned columns), a GuidTimeStamp, a PasswordStrengthEvaluator, and so forth.
Keywords: dotnet|dotnet-core|helper-functions|DropOffStack|binary-search|GridOutputBuilder|GuidTimeStamp|PasswordStrengthEvaluator|helpers-library