In many programs, Ctrl+Mouse Wheel has the effect of zooming into the content (e.g. Microsoft Office or in browsers). In some text editors, zooming is emulated by changing the font size of the editor (e.g. Notepad++), also with Ctrl+Mouse Wheel.

A fitting key binding to do the same thing would be Ctrl+Plus / Ctrl+Minus (Browsers, Notepad++), or Ctrl+Shift+Plus / Ctrl+Shift+Minus (Eclipse)

This is particularly useful when switching between presentation mode (on a projector, where larger fonts are better) and development mode (on a screen, where smaller fonts are better)