Yup, just load up with mp3 or wav files from your PC and plug in the slot! Blue and Me recognises libraries too so you can organise your tunes as well - simples!!
MP3's preferably need to be a constant bitrate, Blue&me doesn't like variable. If you have one an Ipod is a lot less choosy and will play lossless files. That and the Ipod's higher quality D/A converter does give a much sharper, more defined sound.
I haven't tried using it with a usb stick, but I have used my 8gb ipod nano* with it. Mine doesn't seem to like playing with my albums or play-lists. No matter what I try b&m just jumbles the whole lot up and plays them in some random order.
Before you lot say anything no, the shuffle/random features are turned off .
To my (old fashioned) eyes b&m is a great idea but tbh it's a pita.