Top 20 NuGet asynchronous Packages

Automatically login a bunch of accounts to PlayerIO with extreme haste.
Asynchronous Log4Net appenders and forwarder
Stateful implementation on top of Azure Service Fabric's Reliable Actor state manager. Provides common .NET data structure concepts persisted in distributed actor state.
Asynchronous TCP C# library for server applications.
Push stream (IObservable) and async/await (Task) abstraction for processes. Observe processes like event streams.
Build a flexible chained pipeline that can execute the steps asynchronously
Proxy generator for objects with asynchronous constrcutor
RestSharpHelper Small library helper for RestSharp including rate limit, oauth1 support, helper for async download, usage of JSON.Net as json serializer and some helper method
Easy way to implement Event-based Asynchronous Pattern in .NET.
Fully asynchronous memcached client that uses consistent hashing to minimise cache loss if a cache server leaves the cluster or if you add a cache server to the cluster. Built in performance counters so you can see how the memcached client is behaving on your machine and how many requests you are ma...
Minimal, lock-free, IAsyncResult implementation for .NET 4.x
Generic Promises for TypeScript 1.0-rc
Event-based asynchronous http-load testing library.
Http-load testing tool.
Eventing is a library for asynchronous event-driven programming
.NET sockets made easy (Now part of MniakLibs)
.NET Data and Database Extensions
A .NET class library that abstracts away the details of asynchronous network programming. http://github.com/chutch1122/SimpleAsyncNetworking http://simpleasyncnet.cameronh.me/
Thread-safe, asynchronous windows clipboard service with retry strategy for .NET.