Booru Hotkeys v0.5
This add-on has keys for scrolling, paging, adding favorites, and copying a post's id or tags to the clipboard. Having an account for the supported sites is encouraged to use all the keys, but is not required to use this add-on.
Since many of the functions work on the search results (hover over a thumbnail and press a key), an image enlarger is recommended, such as Imagus, which has keys for zooming and downloading images from the search results.
Access your data for site x is used, for example, to know which post to favorite. The tabs permission is used to open links in new tabs, such as opening a post's tag history.