The best tools are:

Phonesweep by Sandstorm
THC
ToneLoc

Phonesweep has probably the best interface.
http://www.sandstorm.net/

the rest look for a link cause as bor said its quite outdated.
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The use of "hacker" to mean "security breaker" is a confusion on the part of the mass media. We hackers refuse to recognize that meaning, and continue using the word to mean, "Someone who loves to program and enjoys being clever about it."
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"Its not a bug, its a feature" (Epic Games)