Paid to review is one of my favourite ways of earning money, but there doesn't seem to be many opportunities to do this. Then I came across Shvoong which pays 10% of their revenue. All you have to do is write abstracts, reviews and summaries on whatever you want.
My favourite things about Shvoong - You earn lifetime royalties from it. You can do as many reviews or summaries as you like so you would have multiple streams of income. It has a low pay out of $10 paid via paypal. If you can't use paypal they do send cheques. You also get free web traffic and the get recognised as a writer.
Things that suck about Shvoong - I don't like the fact there is a minimum payout, although it is low. It would be better if they maybe payed out every month or something along those lines, (I'll have to suggest that to them.) They only pay by paypal so you need to have an account with paypal to earn, unless you come from a country where this is unavailable.
Other information - They show you plenty of ways to promote your work, get it seen by more people and therefore increase your earnings. They also have a forum where you can ask questions etc. They've also just introduced a blog feature.
