Are floating headers and footers good UX?

I'm making a website. I need to put in social media tools - facebook 'like' button and so on. It's been suggested to me that I use a floating, fixed position header or footer for this purpose.

Somehow I can't find an example on a real, live website to give, but I'm sure you've seen them before - a fixed header or footer that keeps its position on the screen as you scroll up or down the page. Perhaps they are minimizable.

Personally, I find these things infuriating, and I use noscript, addblock etc to remove them from the pages I visit. However, I am something of an cantankerous nerd, and my opinions on things like this do not always reflect the opinions of the wider population.

Are floating footers considered good user interface design for modern, dynamic websites, and are they popular with the general public?