There are a number of SDRSharp plugins that extend its functionality. Here is a collection of all the plugins and download links that I could find. The installation of most of these plugins will require editing the SDRSharp.exe.config file with a text editor such as notepad. More detailed instructions are usually bundled in a readme file with the plugin.
Unitrunker Trunking Plugin
Allows the trunking control software Unitrunker to control the frequencies in SDRSharp. This allows digital and analogue trunking systems to be followed.
Download Here

Orbitron Plugin
Allows the Orbitron satellite tracking software to control the frequency in SDRSharp. This is useful as Orbitron can automatically correct for the Doppler shift when listening to satellites.
Download Here
Mirror At the bottom of this page

Frequency Manager + Scanner and Scanner Metrics and Frequency Entry Package Plugin
This is a plugin package which comes with three plugins. It comes with a more advanced frequency manager than the one shipped with SDRSharp.
It also has a scanner option which can quickly scan through a group of your saved frequencies, looking for an active signal.
It also has a scanner metrics plugin, which records frequency activity to a database. Later this database can be analyzed to find out which frequencies are the most active, saving you time searching manually for active frequencies.
Finally, this package also has a frequency entry plugin, which works like the old SDRSharp frequency entry used to work. Basically, it just allows you to choose a center frequency and IF frequency easily by typing it in instead of adjusting it with the mouse.
Download the installation packager here

Easy Scanner Plugin
Another scanner plugin similar to the scanner already shown above. Add frequencies to the database, then use the scanner to automatically find an active signal.
Download from the files section of this Yahoo group. (You will need to register first)

AutoTuner Plugin
Automatically tunes to signals that appear in the spectrum which are above a certain adjustable signal strength. Can also create null areas to prevent automatically tuning to unwanted signals. There seems to be only an outdated version, which is built in to an old version of SDRSharp available.
Download Here

Fast Scanner Plugin
Similar to the AutoTuner plugin in that it automatically tunes to signals above a certain power.
Download Link (Note this site is in Russian, but has a Google translate option at the top of the page. The download link is at the end of the article)


ADSB# Plugin
Runs the ADSB# ADS-B decoding program as a plugin in SDRSharp. The main advantage to using this plugin is that you get to visually see the waterfall whilst decoding. It also adds a 1-bit CRC error check.
Download from the files section of this Yahoo group. (You will need to register first)

DDE Plugin
Allows programs like WXTrack to work with SDRSharp through a DDE interface.
Instructions and Download Link Here.
Audio FFT Plugin
Adds a audio FFT display in the plugin window.
Download Here

ScopeView Plugin
Adds a simple audio scope to the plugin window.
Download Here

A modified version of the scope view plugin with Decimation, HoldOff and Hold options resides in the SDRSharp Yahoo group files section under the name TXmonitorScopeView.zip (you will need to join the group first to download).
Download Here

Simple Audio EQ Balance Plugin
Adds a simple audio EQ balance setting option box in the plugin window.
Download Here

E4000 Gain Mod Enabler
A plugin which allows the E4000 Linrad gain profiles to be used in SDRSharp, via use of a modified rtl_tcp server.
Download Here
Other Plugin Lists
http://sdrts.amoti.ru/perechen_plaginov_i_modifikaciy_sdr___
http://sdrsharp.pbworks.com/w/page/62589136/FrontPage
Source: rtl-sdr.com