Ping Enhancer is a small Windows based program, which will reduce your latency by increasing the frequency of TCP package acknowledgements sent to the game server (all kind of online games).
The program is no longer updated. Last version, 2.0a, released in March 2010, can be still downloaded from the official website.
PingEnhancer vs Kill Ping opinions
Very simple and easy to use. Its free and also takes up less than 1mb of space on my computer. it increased my ping very much.