The first payment proof that you see ( this is the only one that seems to be legible ) is from HCD surveys. As with all of the survey sites I am a member of it's free to join HCD. Cash out is only $10 and the surveys are actually interesting, usually about current events, politics, social issues, etc. Another great thing about this site is they pay you for referrals. It's only 50 cents per person...but in my opinion, it's better than nothing for spreading the word.
The next proof of payment is from Opinion Outpost. This is the second check I have received from them. It's fairly easy to reach the minimum cash out amount since they only require $5. You can either request a check or an online Amazon gift code. Opinion Outpost will also pay you for each person you refer. For each person you refer you will earn 20 points ( which equals $2 ) upon completion of their first survey.
The final proof of payment is from Toluna ( which recently merged with your2cents ). It took a very long time for me to receive my check after the initial request..but they did pay. I strongly recommend using their VIP gift program when requesting payment because there is much less of a wait time. Since receiving the check I've also requested a $43 visa gift card ( from the VIP gift option ) and it arrived in less than a week. Toluna currently has not referral program that I am aware of.
