Whenever I start gnome-terminal, it opens to 80 columns x 24 rows. That is too small for my taste. Henceforth, I want it’s default size to be 80×50. Install gconf-editor.
sudo apt-get install gconf-editor
Start gconf-editor. In the window on the left, navigate to /apps/gnome-terminal/profiles/Default. In the window on the right, set default_size_colums to 80 and set default_size_rows to 50. Be sure to select use_custom_default_size. You are done. Close gconf-editor. Start gnome-terminal and try out its new size. (ctrl-alt-t, if you are using unity desktop)