The Text Size project provides a neat handy little gizmo to let people change the text size on your site. Have users who need a little help seeing text? This is the thing to let users set their preferred size.
It offers a block you position anywhere blocks go. The block has gizmos letting people set their preferred text size. That's about it.
You might wonder -- the browsers usually have a way for users to set their text size in the browser. But hey it's not something I remember that I can do, I wonder how many people either do not know about the keyboard shortcut to make Firefox change text size, or else how many people forget about that. This gizmo puts it in front of people.