Well, you could tune to any kinda chord, which there are about 45, if Im utterly mistaken, that you could tune to.... thats the TYPE, not to which kinda of chord... Let me explain. You could tune to a A#min aug 7th... or a Gb diminished 6th.... but you gotta keep in mind... WHY would you tune to those specific chords... Alternate tunings, as these are named, are usually tuned to major chords, usually. Do anything you want; no one's stopping you. Some musicans, such as Nick Drake/Don Ross, usually play(ed) with alternate tunings at all times. This leads to new possibilities, and can simplify things, in terms of using a slide. Every time you put the slide over the fret line, you have a different chord. Plus, slide can be fun to play. The most common alternate tunings I've seen are open A, sometimes called the spanish tuning... and open E. I prefer A though, due to it' s warmer tone, and what not. Oh, and I dont know why I'm saying this, but Son House used to play in open G. Hope that helped.