The way you can turn it off it to install the Stylish extension for Firefox (which allows user specified style sheets on a per-site basis), use Firebug to find the div id or class of the widget you don't like, and set it to "display: none !important".
Stylish is similar to greasemonkey, which means that you can usually find someone who's already done what you're looking for, and shared it. Here is my stylesheet to make Google reader minimalistic: http://userstyles.org/styles/12663 and here is what it looks like when installed: http://bit.ly/minimalreader You can temporarily disable it with a single click when you want to use any of the hidden widgets.
(All Stylish styles are available as greasemonkey scripts.)
While you can hide the number of likes using other scripts, I did want to see the number. So I moved it to the most logical place. Right next to the “Like link”