List of useful (and free) tools and plugins

Can I suggest a list of popular or recommended tools and WordPress plugins be created as a useful resource, especially for noobs like me.

I could throw a few in to start it off:

G.I.M.P image manipulator
(Freeware version of photoshop)

Insert Headers and Footers
(Wordpress plugin that lets you do what it says - useful to add google analytics tracking code and Facebook code for ads tracking etc.)

WP Meta and Date Remover
(Wordpress plugin that removes the stupid author name and date posted on product pages)

Libre Office
(Free version of Microsoft Office. Useful if you don't have the real thing).