Automating repetitive Firefox tasks is one way to save your fingers from undue stress, and iMacros for Firefox is a great way to do it. From a sidebar you can toggle on and off, and you can run, record, and edit macros. Recording is as simple as pressing a button before starting and clicking another to stop. For more advanced tasks you can turn to a set of demos, but the Web site wiki and step-by-step tutorials were easy enough to follow.
While iMacros can theoretically be used to input passwords, best security practices dictate that you shouldn't. Being able to save macros as bookmarks and being able to share them via e-mail and Delicious are great features, though the plug-in lacks a scheduler. Unfortunately, macros can only run in active tabs, so when you run lengthier ones plan on a long break.