The HeV project offers an open source solution for building “Virtual Private Clouds” with servers that may be indifferently located either within the user organization or dedicated servers offered by many hosting providers.
DMG Automounter is a nautilus script that enables any distribution of Linux to mount a Mac OS X .dmg file (but not install it, since that would require the Mac OS X APIs which are closed source). README has entire install instructions. PLEASE DONATE!
EmuExec is the right answer to make emulation on linux as simple as possible. But it is more than a simple multisystem frontend, you just have to see it by yourself.
EMUFE (Extensible, Multi-emUlator Front End) This is a Front end system for any emulator. This front end runs in full-screen Kiosk tmode rather than a GUI. It was designed to run cleanly from CD-Roms (both LiveCDs and ordinary CDs)
A KDE (QT3) front-end for QEmu cpu emulator. QEMU is a FAST! processor emulator using dynamic translation to achieve good emulation speed. KQEMU makes it easier to launch QEmu directly or create scripts for easy launching of QEmu environments.
PW32 is primarily C runtime library for Win32 aiming to POSIX compliance. Its main concerns are effeciency and support even for low-end Win9x systems. LGPL. Also, PW32 is collection of ported software, aiming to be GNU (etc.) distribution for Win32.