SeaMonkey Extensions compatible with version 2.2 for any regular user. If you are missing any, then it is not compatible. Of course, this is not exhaustive list, so visit frequently for any inclusion.
See more search results etc. on one page, concatenating several pages together...
This extension prevents websites from interfering with your copy and paste actions.
Note: The same functionality is now built into Firefox, you can just change the dom.event.clipboardevents.enabled preference manually.
Adds extension options dialogs to the Tools or Titlebar menu and includes toolbar icon.
CS Lite allows you to set the permission of the cookie every domain from toolbar.
This Add-on allows to have HTML temporarily allowed in the currently displayed message by only one click. When switching to another message, it'll be shown automatically again in plain text or simple html mode (if this is your default mode).
Resize 'Add Bookmark' Popup / 'Edit This Bookmark' Popup, fixes tree selection bug, option to disable popup auto close & Update Url and/or Name of a bookmark with the Url/Title of current page.
Replacement of OpenBook addon
Adds submenus for flipping or rotating to the image context menu.
Launchy will enable you to open links and mailto's with external applications...
Identity Chooser helps you to always use the correct identity when composing a new email.
Remembers last selected (hilited) extension/theme/plugin/userstyle in Add-ons Manager. Turn off/on the add-on selection list box and/or fine tune behavior via its Options.
Paste URL or text to any tabs or a new tab and load it immediately, like 'Paste & Go' feature, but unlike 'Paste & Go', this extension will paste text from clipboard to a tab without focusing on the tab first.