open source

GanttPV - Project Scheduling Software (scriptable, cross-platform, open source)

Open, transfer, and install files by drag-and-drop.

Open CorelDRAW files.

Open any application, file, or folder with function keys.

Open and view XPS documents.

Open ZIP files directly in the Finder and more.

Open, create, and convert archives.

Open, royalty-free media format for the Web.

Open Apple Maps when clicking map links in Safari.

Open MSG and Winmail.dat files.