Low Orbit Ion Cannon (LOIC)

Low Orbit Ion Cannon (LOIC) is an open source network stress testing and denial-of-service attack application, written in C#. LOIC was initially developed by Praetox Technologies, but was later released into the public domain and now is hosted on several open source platforms.
The software has inspired the creation of an independent JavaScript version called JS LOIC, as well as LOIC-derived web version called Low Orbit Web Cannon. These enable a DoS from a web browser. [wikipedia]