You can add a menu extension to Internet Explorer to do most anything.

To add a menu extension to increase the selected text size by +2:

01. Close all instances of Internet Explorer.

02. Create the following Big2.htm file in you %SystemRoot%\Web folder:

<HTML>
<SCRIPT LANGUAGE="JavaScript" defer>
var extMenu = external.menuArguments;
var getDoc = extMenu.document;
var findSeltxt = getDoc.selection;
var createRange = findSeltxt.createRange();
createRange.execCommand( "FontSize", 0, "+2" );
</SCRIPT>
</HTML>
03. Use the Registry Editor to navigate to:

HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\MenuExt.

04. Add a new sub-key named Big2 or Big&2.

05. Add or Edit an unnamed string (REG_SZ) and set it to the expanded path to the Big2.HTM file. If %SystemRoot% is C:\WinNT, set the string to C:\WinNT\Web\Big2.htm. if %SystemRoot% is C:\Windows, set the string to C:\Windows\Web\Big2.htm.

06. Exit the Registry Editor.

07. Log off and log on.

08. Open Internet Explorer and navigate to a Web page.

09. Select a string of text on the Web page.

10. Right-click in the page and press Big2.

NOTE: You could add a Big3, Big4 etc.., changing the corresponding Bign.htm file.