Currently there are two filters available, whereas the Gradation Curves Filter is my main project. The filters are freeware, licensed under the GNU General Public License (GPL).

Gradation Curves Filter:

This filter can be used to edit the gradation curves similar to the curves function of painting programs. It is a powerful tool that allows you to do some basic correction like brightness, contrast and gamma as well as a wide range of advanced color corrections and manipulations.

If you are new to gradation curves take a look at my Curves Tutorial to learn how to use gradation curves. It contains a lot of sample images to demonstrate the effect of different gradation curves.
More information about gradation curves and some other tutorials can be found under Links.

The Curves Readme describes how to configure the filter and explains the different settings of the configuration dialogue.

Version 1.45 (21.03.2008)
Download: gradation.zip

Version 1.46 Beta (24.03.2008)
This version should fix a bug in the curve editor for those who are using a windows DPI setting other than the standard 96 DPI. Download: gradationbeta.zip

Older Versions and the sourcecode can be found under Downloads.
The change log and a bit of history are located under History.

SMP MSharpen Filter:

Original filter by Donald Graft - SMP Support integrated by Alexander Nagiller (13.12.2003)

This filter supports multiprocessors/multicores. Compared to the original filter it gives nearly a doubled frame rate. A performance increase in SMP/HT systems will only be possible using operating systems with SMP support (WinNT/W2k/XP).
Note that this is a SMP version of the original version (1.0) of Donald Graft's filter.
The newer version (1.2.1) of the original filter is highly optimized (assembler/MMX) so you will be better off using that version.
Visit Donald Graft's Homepage for MSharpen 1.2.1

Download: MSharpen.zip

The original filter form Donald Graft can be found at MSharpen Filter for VirtualDub