Siege is great! Really nice and easy to use.<p>Also noteworthy is Tsung[0], which is (far) more complicated but can speak more protocols, be configured to emulate user behaviour a little more closely and send crazy amounts of traffic.<p>[0]: <a href="http:&#x2F;&#x2F;tsung.erlang-projects.org&#x2F;" rel="nofollow">http:&#x2F;&#x2F;tsung.erlang-projects.org&#x2F;</a>