HyperSpin is a flash-based emulator front end for Windows computers for use in arcade cabinets or on your desktop. It's basically a pretty, animated interface that replaces all the shortcuts to emulators you have on your desktop, hides all the supporting programs for joysticks or disc media emulation, and replaces all the various emulator's UI's. It's extremely flexible in that you can add or edit the artwork, systems, games etc. Support for emulators is constantly added and updated mostly by the core devs, and there's a community that is constantly adding themes, game title logos, preview videos, box and media art, game databases, and supporting software.
Visually it begins with a short intro video, followed by a wheel of systems to choose from (ie NES, MAME, GBA), which opens a spin-able wheel of the games for that system. Each system and game has it's own theme - custom animated background, video preview, box and cart art. You can search alphabetically, by your chosen favorites, or by genre. Selecting a game launches it in the emulator you have set up for that game or system. On a desktop you're likely using a wireless xbox 360 controller, in an arcade cabinet you'll be using the built in joystick and buttons - all managed by the front end. While the game is running you can go into HyperPause and read instructions about how to play etc. If you're playing on a widescreen, there is bezel art made to resemble the bezels surrounding an arcade monitor.
HyperLaunch/RocketLauncher is the background software that allows you to set it all up. It split off from HyperSpin to support all front ends like Game Ex etc.
All of this is technically "free", but there is a big incentive to donate and become a lifetime member so you have access to a program that automatically adds and updates all the artwork and videos.
I hope I did a decent job of describing it. I'm not involved in the development in any way.
http://www.hyperspin-fe.com/
http://www.rlauncher.com/
http://emumovies.com/forums/page/portal
