Acoustic guitar, mainly classical and blue/alternative pieces.
Quote: "But I lost my tuner right now and my guitar is way out of tune."
I seriously don't understand how ANYONE can say that (but everyone does!)
naturally, people have a very bad sense of absolute pitch (If you heard a melody in C, and then a week later heard the same melody in E, you would probably remember the melody, but not recognize it's in a different key). It is also super easy to tune a guitar, relative to any one string. (5th or 4th fret=next string!)
So, if your guitar is out of tune, I either congratulate you on your expert sense of hearing, or you haven't learned the super duper easy method of tuning your guitar.
errm... not that I mean to come off mean... it's just annoying

also if you're worried about breaking a string you can turn the lowest string down a couple notches before tuning relative to that string.
[edit]
oh yeah, and of course you can't play a lot of blues/alternative without singing! Cool story I brag about: I went to jam with a person I knew from school, and we couldn't be at her house, so we we were walking around, and this other person was like "Ohei theresa guitar can you play/sing" and I was like "YA" so i did. She said it made her day and I have her phone # so we can jam sometime.
[edit2]
by blue/alternative I Love this stuff:
http://www.youtube.com/watch?v=vrTQ6OtoqfQ, along with classic son house and more alternative spoon/cold war kids/white stripes. I listen to a lot of punk/pop/rock/rap, but I think alternative/blues is the most emotive when you're playing live with an acoustic.
If I ever go to a TGC meetup I wanna get a bunch of people to bring instruments

Is't life, I ask, is't even prudence, to bore thyself and bore thy students?