>>Sorry, looked like a Front-End
no prob. at all. I wasn't very descriptive
re: CPU utilization. It is fairly CPU intensive. At most, 31 games will be visible at a time (28 in the main panel, 7 in the favorites, and up to 3 while scrolling). My PC, a 3.0GHz Core 2 Duo w/ Nvidia 8700 GTX, runs it at about 110-120 fps w/ 70% CPU utilization. My laptop, a 1.06GHz Core 2 Duo, w/ Intel GMA 950, only manages about 12 fps (in-game, it runs at full speed, of course). It is multi-threaded and will take advantage (and requires, I suppose) multiple cores/CPUs.
re: Compatibility. nemulator performs scanline-based emulation, so a couple of games do have glitches (marble madness is the classic example of a game which requires more accurate -- and slower -- per-pixel emulation). My focus is on support for games released in North America, so most of those work. Support for foreign/bootleg games isn't a priority (some work, many don't). Oh, and single games can be launched from the command line.
You hit the nail on the head when you mentioned the ease of setup compared to a separate front-end. Though, to be honest, that's not really what drove development of this. I've been working on this emulator for years now and it's always kind of been a test bed for ideas and programming techniques. I think optimization led to a test to see how many games I could emulate at once, and then it just kind of evolved into this.
I should mention one more aspect of nemulator that I think is unique. All emulators need to solve the problem of syncing audio and video. Most emulators handle this by locking the frame rate to the audio rate. Since this invariably doesn't match the vertical refresh rate of the display, it leads to video artifacts -- either tearing or jerky scrolling. This really kills gameplay for me. If you just lock to the refresh rate (i.e., vsync), then you'll have audio glitches because you're writing to the sound buffer too slow or too fast. I handle this by syncing to the display's refresh rate then dynamically adjusting the audio frequency to keep everything in sync. This is turning into a long-winded explanation, but the end-result is silky-smooth gameplay.