I have what is called sausage fingers. This isn't to imply that my fingers are fat greasy tubes of meat. Sausage fingers' is when I have bad aiming on my keystrokes and mistyping. Usually it comes from not lifting my fingers up enough to key the key just press before I swing my finger types to the next key. Hence the key next to it gets pressed as well.
Basic typos are also a frequent nemesis.
The letter out of wack is almost always next to the key I should have pressed, be it above or next to it. But when I look at the keyboard, the transposed letters aren't next to each other. This is sort of odd, but few things make me worry a bit more. Think' doesn't become 'thino' and 'it' doesn't become 'ik'. This isn't just one way, if I try to type 'thing', I'll usually get 'think' and vise versa.