Once you`re viewing the keyboard, tap the "?123" button to get to the numeric keyboard, then,
once you see the numeric keyboard, tap the "1/3" button (==Page 1 of 3 Numbers and Symbols).
The underscore will be in the top row of Page 2, third from the left.
PS: Smileys are on Page 3 of 3.
I foolishly used an underscore character in a user name, and I can't find it on the Samsung Galaxy S2 keyboard, so I can't log into the android version of flickr!
Anybody know where the character is? This _ is the character I'm looking for.