[andrewflnr]

What do you know, there's an xkcd for that too: http://xkcd.com/1105/

[thelukester]

If I could change one thing about human history, I'd remake the 0 and O's (# and letter) and the I, l, and 1 (letter i, letter L, and #) so you could never confuse them in hard to read CAPATCHs.

[Keyframe]

Depending on the font sometimes even 5 and S and 8 and B too.

[lostlogin]

Having 0 and o next to each other on a keyboard is great too.

[bandy]

There's a relevant XKCD for every situation.