SuperOneClick v1.7 (Root, Unroot, Enable Non-Market App)

You can get it from shortfuse.org

ere's a one-click root with almost all phones and all android versions. (including the i9000, Droid, Nexus One, etc)

YOU CAN ROOT ALMOST ALL ANDROID PHONES!

The program requires Microsoft .NET Framework 2.0+ or Mono v1.2.6+
Operations systems with native support:

• Windows Vista
• Windows 7
• Ubuntu Hardy (8.04 LTS)
• Ubuntu Jaunty (9.04)
• Ubuntu Karmic (9.10)
• Ubuntu Lucid (10.04 LTS)
• Ubuntu Maverick (10.10)
• Debian Lenny (5.0)
• Debian Squeeze (testing)
• Debian Sid (unstable)
• Debian Experimental

If you run Microsoft Windows XP, install .NET Framework v2.0 or above
If you run Mac or another Linux flavor, make sure you install Mono:
http://www.go-mono.com/mono-downloads/download.html

For more information about making it work in linux:
See here