Here’s a new open source Windows SDR application. According to the developers, “SDR# (read SDR Sharp) is a simple, intuitive, small and fast PC-based DSP application for Software Defined Radio. It’s written in C# with both object design correctness and performance in mind. The main purpose is to offer a simple proof of concept application to get hands into DSP techniques. It supports SoftRock, FiFiSDR, FUNcube Dongle, SDR-4 and any sound card based SDR front end.”
The program’s setup instruction page makes no mention of the RTL-SDR, but users of that hardware may want to give it a try.
You can download the application and source code from SDRsharp.