Greasemonkey gives the user more control over the UI

Some interface designers may feel threatened by the idea of Greasemonkey scripts altering the intended look-and-feel of their web pages (at least in Firefox and Mozilla), but I like the idea of users getting more control over their experience (even if the scripts are brittle and sometimes hack-y), and in the best scenario I would imagine you could improve a site’s design by selectively adoping popular interface improvements.
Mark Pilgrim, the guru of Atom and Accessibility who wrote the Greasemonkey script Butler (which removes ads from Google results pages among other things) and the online tutorial Dive into Greasemonkey, has now written a book for O’Reilly called Greasemonkey Hacks:

More than just an essential collection of made-to-order Greasemonkey solutions, “Greasemonkey Hacks” (O’Reilly) provides complete, fully developed user scripts you can use to modify web pages, the tools to customize these scripts, and the guidance to develop your own scripts from scratch. You’ll learn how to:

  • Install, configure, and debug your first Greasemonkey script
  • Insert links into web pages, fix broken pop-up links, and follow links without clicking them
  • Beautify the Web by enhancing fonts, images, tooltips, lists, and tables
  • Intercept and modify web forms, generate developer reports, and debug Ajax web applications
  • Make search engines auto-complete your search terms, prefetch your
    results, and remember where you’ve been–without invading your privacy!
  • Add accessibility features that make sites easier to read and navigate
  • Download embedded movies, automate site registrations, and route around brain-dead browser sniffers