Digital Trends put together this interesting year-end list of some of the best plugins of 2012. Most of them cost $15 or so, but some are free, including a few I’ve used for some time: All in One SEO Pack, Akismet and WPtouch. Most of the others on the list look interesting. Among them are FontPress, which allows you to customize text on a WordPress site; Sexy Bookmarks, which is part of Shareaholic; and Visual Composer, which allows you to create custom pages.
Here are others I highly recommend. They are all free.
Ozh’ Admin Drop Down Menu. I can’t live without this one. It puts all of the dashboard functions into a drop-down menu at the top of the page. I find that it makes working with WordPress much easier and more intuitive.
Ultimate TinyMCE. This plugin allows you to add functions to the posts toolbar. It also allows you to organize the toolbar in ways that suit your style of working. I especially like the ability to increase point size and change fonts. Also check out TinyMCE Advanced.
Broken Link Checker. This plugin monitors links you’ve added to posts and lets you know when they’ve gone dead.
JetPack by WordPress.com. This is really several plugins and widgets in one package. Those include a mobile theme, a CSS editor, and a good statistics package.