I think I know what you are saying, but I think I might prefer the text.
One problem I forsee is how do you set the upper limit on the rate? I suppose you could default to CD-quality, but using MP3's uses only (roughly) a quarter of the bar, and even using flac or ape probably only half to 3/4. And, the scale for each of them is different, so you'd need to adjust the bar for each type.
But, visually, it would be kinda cool. Or maybe a "speedometer" type.
