Back to the days when I used KDE (that was more than a year ago), I got used to the Shift+Up and Shift+Down keybindings in Konsole (I have to say it's a great terminal emulator). These keys combinations scroll up and down, respectively, a single line of text.
When I later switched to GNOME, I was quite disappointed to see that these were not supported by gnome-terminal. In fact, this may be false, but I didn't spend too much time looking for it because gnome-terminal is way too slow.
So I switched back to XTerm, the genuine terminal emulator which, at first, seemed to not support these key combinations either. As I was aware of XTerm being highly configurable, I spent some time reading the manual until I figured out how to set scrolling up.
What I found is that XTerm can map any key combination you want to one of its integrated functions, so all I had to do was to map Shift+Up to scroll-back(1) and Shift+Down to scroll-forw(1). In other words, I had to add the following to the ~/.Xresources file:
*VT100.Translations: #override Shift <Key>Up: scroll-back(1) n Shift <Key>Down: scroll-forw(1)
While we are at scrolling, here is another little trick which will increase the amount of lines stored in the terminal backlog:
XTerm*saveLines: 512
Reload your X settings (xrdb -m ~/.Xresources) and you are done!
