Agreed. Recognizable lyrics is usually not good, unless its music that'll pump me up when I need it.

I've been trying out listening to some sort of white noise, ie. running water, static, etc., borrowing from the idea on this post: http://cameronmoll.com/archives/2008/11/showering_and_thinki...

It can get pretty noisy where I work, so something that distracts me so constantly and blocks the noise out helps me focus.