I use Noscript, Ghostery, & AdBlock Plus
I added Flashblock because I hate when websites start blaring out videos when you open them.
Remove this Permanently lets you choose elements that you never want to see, like ads, buttons and advertising videos. It has a lot of options. Right click on an area and a menu box shows the options. Hover over the option you want and it will put a red line around what will be removed so you don't remove too much. Handy for pages where I have to disable ad blocking to read the text. I just Remove the ads and they don't come back.
Also handy:
HttpsEverywhere sometimes breaks websites. For some reason, pcworld.com shows a blank page every time. I have to use Internet Explorer to view it. I keep Internet Explorer without addons, for some websites I can't otherwise view.
Hola Better Internet can be used to get around country blocking. I have it disabled unless I need it.