When listing a large set of data alphabetically Is it better to list them horizontally or vertically? Craiglist lists states in columns vertically. Another site I've been using http://www.rent-acoder.com/ lists the project tags in rows horizontally. Vertically makes sense because you scroll down naturally to view more text. But horizontally also makes sense because humans read left to right, then top to bottom. What is more natural from a ux point of view?
Edit:: Also, would it matter how much content there is to display? If there were a list of say 4 columns x 2 rows, it seems cumbersome to scan up and down, up and down alphabetically. And if it's 2 columns by 4 rows, it seems cumbersome to go left right, left right.