Nearly a perfect tool, but as some may have wrote:
1. needs a font-preview (a not full char font looks wired on foreign languages, consider that)
2. need better mass install or uninstall (check fields)
3. needs to show source of the font to install the font directly in the OS (sorry dev-lad, must of us noobs use WINfool and not LINfast ;)
4. option to chage font size

nice but not the job of this Addon

1. option to manipulate the webpage (forcing the font change on hardcoded sites)

2. Needs Payment button for Dev-Support :)