Greasemonkey is a plug-in originally for Firefox but also available for Epiphany which lets an end-user run javascript to customize the look and function of websites.

Here are my greasemonkey scripts.

Debian lists

all the scripts at once

Most of my scripts are to improve the look of the Debian mailing list archives I will shortly be moving these into a git repository anda also providing a one-size-fits-all javascript file that implements the lot.

Access Keys

Add access keys for navigating around mailing lists.

Collapse threads

Add "Collapse" and "Expand" buttons to thread views which allow you to collapse/expand the tree of posts.

Nice quotes

Convert the plain-text quotes in emails into HTML blockquotes and style them accordingly.

This script also detects and styles signatures to mails, and is slowly evolving to undo some of the damage of HTML mail too.

use DLs for header lists

Convert the unordered-list of headers into a DL (descriptive) list. Apply some style to make it take up less space. Finally, hide most of the extraneous headers.

See also

If you use mutt, you might like Martin Krafft's mutt-mailto script