[orrinward]

There are plenty of services that are paid and not set up in your best interestes (Profit Accumulator is the most popular these days).

If you're interested I highly recommend the MoneySavingExpert Matched Betting forum - http://forums.moneysavingexpert.com/forumdisplay.php?f=41

It is free, unbiased (lots of the specifically tailored sites like PA mentioned above have affiliate deals which reduce the amount you can earn) and active.

Discussion on the MSE forum is restricted to what they define strictly as "risk free", not "EV+" opportunities, but that's a healthy start.

Their definition of risk free is making a guaranteed profit regardless of the outcome - Either natural arbitrage or an offer-dependent forced arbitrage.