I have a server client application. The clients sends the server http posts with info every second or so. The server is implemented using C#, there server doesn't need to respond in any way to the client.
Whats the easiest and most practical way to get this done? Is there some kind of library that is easy to use that I can import into my project.
Why not just use a regular old web service? It sounds like you have simple functionality that doesn't need to maintain a connection state. With a web service, you can simply expose the methods to your client, accessible via HTTP/S. If you're already using .NET for your client, you can simply add a web reference to your project and have .NET do the heavy lifting for you. There wouldn't be any need to reinvent the wheel.
You can use http.sys to create your own http listener without IIS or additional overhead. Aaron Skonnard has a good article here.