Legal solutions for crowd payments in Europe?

I would like to launch a startup based on crowdsourcing: many people, potentially ten thousands, would provide some information through a website; in exchange, they will be paid once they accumulate enough credit (e.g., 20-50 euros). In my own country (in Eastern Europe), this is legal only if there is a paper, signed contract between the company and the payee, which is not feasible for large number of payees. What are the startup-friendly countries in Europe where it is legal to make such payments exclusively through online interactions, and what are the legal constraints for such a process in these countries? Google does it from Ireland for its Adsense program, so Ireland must be one of the solutions. What about UK or Cyprus? Are there any existing payment solution providers that are specialized in crowd payment (i.e., one to many payments instead of the more common many to one or one to one payment providers)?