MAME (Multiple Arcade Machine Emulator) is a free, open source arcade game emulator for Windows users, it is also the most familiar to players from all over the world and one of the most commonly used game emulators.

JPCSP (short for Java PSP) is the first one PlayStation Portable (PSP) emulator designed for PC, with which we can play PSP games on the computer. Along with its biggest rival - PPSSPP, they are the best 2 PSP emulators now.

Audacity is an open-source and cross-platform (Windows, Mac OS X, Linux) live audio recording and editing freeware. It is developed under Linux, has a point-and-shoot operation interface and professional audio processing functions and effects.

As a matter of experience, many people (especially for personal webmasters) have deeply understood the installation of Apache server on localhost is definitely not an easy thing, not to mention adding a MySQL, PHP or Perl component, harder. Nevertheless, luckily there are tools similar to XAMPP integrate frequently-used development environments into one package.

Anki is a friendly, intelligent spaced (word card) learning system based on the Spaced Repetition theory. It's free and open source, with which you can remember anything, anywhere and efficiently.