I found this in a few different places around the 'net - hopefully it's helpful:

Change Web Page Font Size on the Fly

If your mouse contains a wheel for scrolling, you can change font size on the fly when viewing a Web page.

• Press and hold Ctrl.
• Scroll down (or towards yourself) to enlarge the font size.
• Scroll up (or away from yourself) to reduce the font size.

You might find it useful to reduce font size when printing a Web page, so that you can fit more content on the page.

Dani,
Thank You so much for that tip. My 3 year old was pushing keys as I was surfing the net and everything went to small fonts. Which made this extremely difficult when viewing my WebPay page. I now know how my little angel did it (while I was scrolling down on something). Oh thank You so much. Laura Z

This is a really useful trick. Thanks