But I guess the main thing I was commenting on was, you don't want to make the casual surfer have to go and adjust their computer speakers to compensate for a low level mp3, Scott...

Few will bother, then you have the problem of sounding anemic compared to your competitors..! I agree that, for CD's, it has gotten quite out of hand, the 'volume wars' between record labels, to the point of making some stuff quite unlistenable, but the web surfing experience, especially for commercial purposes, needs to take into account that comparisons ARE being made, and you need to put your best foot forward to give yourself the best opportunity to make the sale...

It's not like you need to go to a professional mastering engineer (though I wouldn't mind the business!), but a small amount of compression and limiting will go a LONG way to making your site stand out as 'professional'