If you run a personal finance blog or that sort of website then there are lots of survey sites you can promote in return for commission.
VoxPopMe is a free mobile app for Android and Apple that you can use to earn a bit of extra money.
Clickworker is a crowd-working website where you can earn money by doing quick and easy small tasks.
Clixsense is an online rewards website. It was first founded in 2007 so it’s been around a long time!
They have a wide range of retailers and service providers that you can promote. Including some premium brands. See details and reviews now.