Gener8ads is a browser extension for Chrome and Firefox which acts as a kind of adblocker - it replaces most of them with cute pictures of pugs! Other ad replacements include positive quotes and pretty landscapes.
For every replacement ad the plugin provides you, you'll earn tokens. These can then be exchanged for Paypal cash and gift vouchers on the Gener8 marketplace. Only a certain number of each are released each week, so you might want to set a reminder for the time they go live. Even if you miss one week, you'll build up more tokens for a better prize the next, so it's not a total loss.
The best thing is that the rewards are quickly achievable, rather than having to spend months building up to a couple of quid. You can get discount vouchers from a single token, and a £5 Amazon voucher will set you back 50 tokens - about a week worth of browsing. You get 10 tokens just for signing up with a referral link, plus another ten for every referral you make.
Give it a go by clicking the picture link below and bag yourself some extra cash!