pchorman- I would love to take that challenge, even though I probably couldn't guess which is which. I listen to MP3's everyday and many times I am fooled when someone tells me how he achieved that sound. I probably couldn't be fooled as easily if the songs were on CD and I was listening through my stereo system, instead of my computer speakers.
If you post it make sure you don't smother the sound in effects, or better yet just use a small bit of reverb and nothing else.
There are at least a dozen of these things on the market. J-Station, Pod, Sansamp, V-Amp, VG-88, DG-Stomp, RepliTone, zenTera, GT-5, etc. I'd love to have all of these in my studio for a couple of weeks and see what they're all about.