The IF Average tool is a RTL-SDR compatible plugin for SDR# which allows you to plot an average of the current spectrum shown in SDR#. This is especially useful for radio astronomers who often need to average the spectrum for a long time in order to get a good plot of the Hydrogen Line. Recently the plugin was updated to support newer versions of SDR# and to upgrade some features. Daniel Kaminski, the author of the plugin writes:

I used ultrafast FFT which works on 4k to 512k bit space. With this plugin it is possible to average up to 64000000 samples in real time. XNA allows to shows the calculation results in real time.

To install the plugin you will need to install the XNA Framework 4.0 Redistributable first. Then copy the plugin files over to the SDR# folder and add the “magicline” to the SDR# Plugins.xml file.