When you are zoomed in to read, for example, a column of text in Safari on the iPhone and iPod Touch, it can sometimes be hard to scroll in a straight line without accidently scrolling left and right. I found this quite frustrating until I changed the way I was scrolling.

The important thing is the direction you start dragging in when you scroll. If you move only vertically then the scroll becomes vertically locked and will not scroll on the horizontal axis until you next lift your finger. Conversely, starting a horizontal drag locks scrolling horizontally. The problem is that it's too easy to start off on a diagonal and drag the column you're reading sideways.

If you scroll by running your thumb along the very edges of the screen then you can always be sure you're moving in a straight line and you won't suffer this anymore. This has the added benefit of keeping your view of the screen uninhibited since your thumb can be practically off the display entirely. Additionally, it's possible to scroll a long page like a forum thread continuously by starting a new drag with the opposite thumb even before you reach the top or bottom of the screen.

I created a short video demonstrating this scrolling method, in case you'd like to see it in action.