DoubleCommand started out as a hack of iJect, which was generously GPL'd by Christian Starkjohann. So go check out the great software he makes over at Objective Development www.obdev.at.
Called DoubleCommand because originally it was used to give the old PowerBooks a second Command key, where there was an enter key.

Version History

1.7 - 2013-10-27: DoubleCommand 1.7 adds support for Mac OS X 10.9 (Mavericks).

1.6.9 - 2009-11-24: DoubleCommand 1.6.9 adds full Snow Leopard (Mac OS X 10.6) and 64-bit support.

1.6.8 - 2009-03-10: DoubleCommand 1.6.8 adds back the missing options from the preference pane.

1.6.7 - 2009-02-05: DoubleCommand 1.6.7 fixes the control key under certain situations, and adds an uninstaller script.

1.6.5 - 2007-08-06: DoubleCommand 1.6.5 removes the unnecessary log output.

1.6.4 - 2007-07-25: DoubleCommand 1.6.4 adds Caps lock to delete feature for the Colemak keyboard layout. Also added internals for multiple keyboard support.

1.6.3 - 2007-06-27: DoubleCommand 1.6.3 allows using the Option key with backslash as forward delete to delete to word boundaries.

1.6.2 - 2006-12-04: DoubleCommand 1.6.2 fixes two bugs, Command flags still active after using PC style home and end, and allows both shift keys to trigger the forward delete feature.

1.6.1 - 2006-05-01: No longer beta, since it seems stable enough to use everyday.

1.6b3 - 2006-03-08: Compiled as a Universal Binary, should work on Intel Macs.

1.6b2 - 2005-12-16: Added a debug output option.

1.6 - 2005-08-18: Now with support for Mac OS 10.4 (Tiger).

1.5.5 - 2005-08-18: Fixed bug with backslash to forward delete.

1.5.4 - 2004-04-12: Added support for Enter as Forward Delete, and support for the new PowerBook's enter key.

1.5.3 - 2004-12-17: Fixed Command -> Option bug (not clearing Command flag), added Control + Home/End PC style.

1.5.2 - 2004-08-10: Enabled right side modifier keys under 10.3.

1.5.1 - 2004-07-16: Removed system log output, created an installer package including a new preference pane.

1.5 - 2004-06-09: Updates some internal key codes for Mac OS X 10.3 (Panther).

1.5b3 - 2003-11-24: Fixes the shift delete as forward delete feature for Panther, adds kernel panic protection.

1.5b2 - 2003-11-11: 1.5b2 released - fixes the enter as fn key feature for Panther.

1.5b1 - 2003-11-11: 1.5b1 released - fixed for Panther (10.3) and compiled with Xcode.

1.4.4 - 2003-11-04: 1.4.4 declared final.

1.4.4b6 - 2003-10-27: Fixed shift delete as forward delete for Office, fixed a bug in home and end keys, added F12 and eject swapping, fixes for function key swap for some PowerBook keyboards.

1.4.4b5 - 2003-10-15: Fixes for fn to control, support for TiBook function key behaviour swapping.

1.4.4b4 - 2003-09-26: Many fixes for capslock to control.

1.4.4b3 - 2003-09-16: Fixed the enter key to command key problem.

1.4.4b2 - 2003-09-15: Fixed the power key problem, fixed the sticky capslock to control feature.

1.4.4b1 - 2003-09-04: Fixed the stick fn key problem, changes to the f key swapping feature (needs more testing).

1.4.3 - 2003-07-16: Added real function keys, disable capslock and also much improved install and config system.

1.4.2 - 2003-06-04: Added backslash as fwd delete and also much improved install and config system.

1.4.1 - 2003-02-07: Compiled with new compiler for smaller binary, also PC home and end keys.

1.4 - 2002-08-30: Quick recompile to support Mac OS X 10.2.

1.3 - 2002-07-19: Code tidy and added capslock becomes control and other features.

1.3b2 - 2002-06-06: Fixed a kernel panic with Mac OS X 10.1.5.

1.3b1 - 2002-05-01: All versions joined into one, now configurable at any time!

1.2.2 - 2001-12-15: Removed Shift-F12 option since it interferes with the Shift+Delete feature.

1.2.1 - 2001-10-23: Fixed problem with Deluxe that blocked the Command+Shift+Delete empty trash key shortcut.

1.2 - 2001-10-22: Added Shift-Delete feature, split into standard and deluxe versions.

1.1 - 2001-10-21: Fixed keyboard bell and enter key event problem. Fixed Command-Tab problem. Fixed page jump problem in BBEdit.

1.0 - 2001-10-16: Initial release.