Zooming in and out in the terminal of Ubuntu is easy and convenient. Zoom here means the font used is increased or decreased in size. Programs like Vim work transparently on zoom, adapting to the new zoom by showing more or less lines of text. This can be a good trick to zoom out to get a good view of the code in Vim before zooming in on the details.
The default keyboard shortcuts to zoom in and out are straightforward:
Ctrl and plus keys and
Ctrl and minus keys. Note that you need to press the Shift key too to get the minus.
Tried with: Ubuntu 12.04 LTS