A very interesting approach to guitar tuning by Ralph Patt: http://www.ralphpatt.com/Tune.html
It turns out to be more than just convenient for modern music especially jazz. Having very little experience with rock I'm not sure about it, but all scales, chords and arpeggios become easier to play with this approach. One of the greatest things about it is that fingerings do not depend upon sting set - those five positions we used to learn with classic tuning are not needed anymore. Learn one position and use it across the neck.