Script Summary: Focus Input on a Search TextField
Useful for search pages - put the focus in the searchbox so you can start typing directly.
You can edit the matching pattern in the script if you have a site that uses a different name for a search-textfield.
UPDATE: On request, I have added a keyboard shortcut and an GM menu command to change the behaviour from automatic to keyboard controlled!
press Ctrl + , (komma) to put the focus in the first matching input textfield