Business Software and Services Reviews | G2 Crowd is a software review and comparison website oriented towards business software, but open to all kinds of other software and web services.
They will pay out $5-$10 Amazon gift cards if you log in with a Linkedin account and review some of the software there. More obscure, less-reviewed software get better payouts.
For my two entries they sent me my GCs within 6 hours.
I'll try to list some review prices that I come across: