gPhoto is a program and library framework that lets users download pictures from their digital cameras. The libgphoto2 library gives you access to hundreds of models of digital cameras on several platforms. GIT repo and Issue tracker lives at https://github.com/gphoto/ these days.
Run Windows applications on Linux, BSD, Solaris, and Mac OS X
Wine is an Open Source implementation of the Windows API on top of X and Unix. Wine provides both a development toolkit for porting Windows sources to Unix and a program loader, allowing many unmodified Windows binaries to run on x86-based Unixes.
The Coconut Library is an Objective-C class library for PC-UNIX systems and MacOS X. This library is designed to develop software which works unix systems and MacOS X. And depends on Cocoa library for MacOS or Cacao library for unix systems.
The Meldware Communications Suite (MCS) is a platform-independent groupware package consisting of: Meldware Mail, Meldware Calendar, Meldware Webmail, Meldware Secure Administration System. It provides IMAP, POP, SMTP, iCal, WCAP, and Webmail services.
Internet Control Firewall Intrusion Detection and Logger for Inbound and Outbound Traffic. Watches Files and Directories, Drive and Memory Protection.
GOK is an on-screen keyboard. An alternative to the mouse/keyboard input system (for unix-like systems with GNOME libraries.)