Top 20 NuGet .net4 Packages

Really Simple Service Discovery Protocol - a 100% .Net implementation of the SSDP protocol for publishing custom/basic devices, and discovering all device types on a network.
A library for dealing with streams in .Net.
A transactional file manager for .NET. Inspired on ChinDo's implementation
MVC utilities
Build.Mvc is a helper extensions method library that turns the standard ASP .NET MVC 3.0 HtmlHelper methods into jQuery-style chainable methods that allow you to expressively add markup and style to your MVC application.
ASP.NET MVC and HtmlTags integration. HTML controls builder.
SqlServer - Elasticsearch Sync
An client RPC library (abstract + Json RPC 2.0 implementation) for .Net.
A Ninject extension for Prism Update with strong name support
Logger facade
A set of utilities
Implementation for log4net
CommonSharp - A collection of useful C# classes and static methods
You probably want Spooky.Json20, not this package. Spooky is a client RPC library for .Net, providing an abstraction layer for RPC calls (using sytems such as Json RPC).
Build.Mvc is a HtmlHelper extension library that turns the standard ASP .NET MVC 5.0 HtmlHelper methods into jQuery-style chainable methods that allow you to expressively add markup and style to your MVC application.
ASP.NET utilities
Utilities for Autofixture and Entity Framework
Utilities for Autofixture and AutoMapper
Utilities for Autofixture, Xunit and AutoMapper
Unit tests Data Access implementations for Entity framework