99.9% of them are probably rip-offs.
The only work-from-home job I know of, that is genuine and pays reasonable rates, is working for Deya as a routechecker.
Deya is the company which delivers all of the UK's Yellow Pages (and many Phone Books, and other directories, as well). Routecheckers phone customers to check that they've received their directories. All calls are routed through Deya's phone system and so are free to the routecheckers.
I've not done the work myself but I do some casual work for Deya, supervising deliveries across a wide area. This involves me liasing with routecheckers and I know that they all seem to enjoy the work.
I'm not sure how much work each person gets (or if Deya are currently recruiting new staff) but it might be worth looking into:
http://www.deya.co.uk/index.aspx?pageref=5130
Chris