We don't offer a text re-size widget on our site because we believe that your browser does it better than any website can.
Essentially, in any site you can use these key combination to make the text larger.
- CTRL and + will make the text larger in Windows
- COMMAND and + will make the text larger in a Mac.
If you are unsure how to re-size text on any site, please watch this video:
The BBC has a great description on My Web My Way on various ways to change your text size in any browser & operating system.
If your browser doesn't support this, then it's time to upgrade to the latest version of Firefox, Opera or Chrome. For more information on why this is a problem see articles on 456 Bereastreet, Drupal Groups or Accessify & WebAIM
I've attached below screenshots for the Mac with the screens to to set minimum font sizes in Firefox (need to click on the advanced button), Safari & Opera. It's essentially variations on Preferences -> Content -> Fonts -> Advanced -> Minimum font size: 18.
Webaxe did a great job summarizing the thread on twitter that inspired this post No to Text Resize Widgets. There is also a really interesting discussion thread on textsize in Drupal Groups.