iNdependence is a Cocoa-based application for Mac OS X which provides an easy-to-use interface for jailbreak, activation, SSH installation, and ringtone/wallpaper/application installation on your iPhone. It's open source under the GNU v2 license.
What's new in iNdependence
Fixed bug where, if the iPhone software download directory doesn't exist, iNdependence fails to jailbreak/activate (thanks to Adam Elliot)
Added Danish localization (thanks to Daniel Flugt)
Added code to autodetect the correct offsets for the private MobileDevice functions used. This will prevent the need to update iNdependence on every little iTunes update.
Made it so that, even if the private MobileDevice functions are not initialized, iNdependence will still run (it just won't allow jailbreak and SIM unlock)