Toggle all features from the Bugzilla Preferences link on every Bugzilla page. Works on any Bugzilla Installation. Features:

Show all changes to the bug inline. (This is really useful.)
Image attachments or links to images are shown inline as thumbnails.
View images as a lightbox.
Styled comments.
Temporarily removed: Github commits are shown inline if linked to in the comment.
Gravatars next to comments.
Add a scroll bar if the text in the comment is too wide.
Remove flags, status and blocking options (off by default).
Remove access keys (off by default).
Hide the first comment if there's nothing in it.
Hide "CC" items from history
Show bug status (closed, etc) on inline history.
Option to hide "nobody@" bugs from bug lists.
Remove "Bug" from the title, so it's easier to see the bug number with a lot of tabs.
Automatically select component and product for "Clone Bug" link.
Add "new" link to depends and blocks fields
Don't guess OS or Hardware (off by default).
"Open all bugs in tabs" link for lists

Notes