Ha, It's kind of weird for me, I have no problem finding shirts whatsoever, I wear a large, simply because of my height (I'm right around six feet even.) All of the fabric, for the most part, from these large t-shirts goes toward the length, since I'm incredibly thin/lean/stick-like, etc, so I've never had a problem with a large not being long enough.

The real trouble when I'm clothes shopping is finding shorts and jeans. I live in the Southeast in America, so jeans for really skinny people aren't in as high demand, at least from what I see on store shelves. I wear a 30waist X 33 length pant, and 30 waists are few and far between. most of the time I settle for the slightly more common (though still hard to find) 31 waist, and I wear a belt.