Good MP3 Transposer software?

Any good software out there for transposing MP3's.
I heard of audacity?

thk

Audacity is free, and has effects to change the pitch & change the tempo, independently. You can also change the "speed," which moves those 2 in tandem, i.e., like a tape or "record" player would. There are limits, e.g., a few half steps, on what you can do before it starts to sound weird, though, so depends on what you are trying to accomplish.

I'm sure some of the pro plug-ins can do a better job with some things, but I don't have any experience with those.

thx
yea, the max would be 2 1/2 steps, or 1 step...semi-tone