Open Directly is a plug-in for Lightroom 2/3/4/5 that opens images directly in another program. That other program may be another raw converter, or any program the user chooses. In either case, the plug-in simply sends the original file and invokes the other program.
Other raw converters
Some Lightroom users want to manage raw files in Lightroom but use another raw converter to adjust them. Unfortunately, Lightroom's Edit With command generates a TIF file rather than sending the raw file itself. Dragging the thumbnail to the other raw converter program's icon isn't much use when you work in full screen mode. Another alternative, Lightroom's Export command, can launch the other raw converter but only by generating copies of the raw originals. Open Directly was originally intended to get round these problems.
Not just raw files, not just raw converters
You aren’t limited to raw converters - you can send photos to any other program.
For example, here one "editor" is set to Mac's Mail application and another is HoudahGeo, a program for geotagging photos. You can add up to 6 different programs and while programs like Excel or Dreamweaver might be amused to receive a batch of raw files, there are no restrictions on the apps you can choose.
Payment and Updates
The trial version only allows one external app to be set up.
Purchasing the plugin will give you a registration code that will remove this restriction. All future updates are free.