Another online survey site which I sometimes use is called OpinionWorld. Like most survey websites, to start off registering is needed, which from memory took a little while. Once registered, the email invitations to surveys commence relatively quickly.
I receive on average about 1 invitation a day. However, the majority of these are for small surveys, in which nothing is earned and instead a donation is made to a charity. This charities do change, and I assume that the donations are actually made. In addition there is an entry into a prize draw, but as of yet I have not won anything in one of these.
Approximately once or twice a week, however,emails are sent out which have surveys accompanied by a cash reward. In my experience this cash reward has always been either £1 or £2 but I believe that other rewards are available for different surveys. Unlike other sites there is no need to wait for a limit to be reached before the cash can be accessed, with OpinionWorld the money is transferred for each survey separately. However, like Valued Opinions which I also have experience of, there is a delay before the reward is accessible, which can be up to 6 weeks, but I have always received my cash in the end.
The cash is sent via PayPal, so there is a need to have an account for this (which has to have the same email address as the one you use to register to OpinionWorld. Whilst this is easy, it can be frustrating getting paid £1 and not being able to use it, since PayPal has withdrawal charges which I for one am loathed to pay!
All in all though I would recommend OpinionWorld and have definately not found it to be a scam as I have always been paid on time.
Update: As of August 2009 I have started to receive emails which instead of offering £1 per survey which is deposited automatically into a PayPal accoutn 100 points are earned instead. These points are accumulated until 1000 are reached. Once this is achieved, it is possible to get £10 sent to a nominated PayPal account. Whilst this means that each survey is worth about the same as previously, there is the need to wait for this payout level to be reached, the lack of which was one of the biggest advantages to OpinionWorld. Apart from this all OpinionWorld surveys remain the same, including the option to support a charity after every survey is completed.