First of all, only bloggers can take part, and they can sign up at their site by submitting their blog and the required information. Then the ReviewMe staff checks your blog for your traffic rankings and such, and then accepts or rejects your blog. Once you are accepted into their marketplace, you can accept reviews from advertisers in two ways. Either the advertiser selects your Blog directly (called Prime reviews), or the advertiser requests for a particular amount of reviews from any blogs. In the latter instance, you will be alerted in your home page at ReviewMe about the number of reviews on offer right now.

As shown here, if you see any reviews on offer, act quickly. Click that link (the one with the number of offers) which will take you to a page where the reviews will be listed. Click on any review that you think matches the theme of your site. Accept review and then you will be provided with a deadline to submit your review, which will come up in your home page.
I said act quickly, because once any other blogger takes up that review and the number of reviews the advertiser ordered has been met, you will no longer be able to take that review even if you reached the review accept page. One quick way to be alerted as soon a review offer is put up is to subscribe to their campaign feed. Click the feed icon shown below, and the feed will be added to your feeds tab in IE or Opera and you will be alerted as soon as any new review offer comes up.

Also the deadline you see before accepting a review is no the actual deadline. You would have to submit the review URL much sooner than that and be prepared for that. ReviewMe cancels your URL submission page once you reach the deadline shown. You will get on an average 2-4 days to write a review.
Pros
A very prominent feature of ReviewMe is that they pay very quickly. Payment is usually through PayPal and you are usually paid by the 5th of every month if your payment balance meets the minimum amount of 25$.
Alternately you can also sign up for a Payoneer MasterCard Debit card through ReviewMe. You will be accepted only if you are a blogger receiving regular payment from ReviewMe. They support international customers too. This is an easy method to get you a MasterCard to verify your PayPal account; though a word of caution- Payoneer fees are a little high. Check their various fees before signing up.
ReviewMe also offers reviews to you on a regular basis. You are sure to get at least some 5$ reviews every month, even if your blog has medium or very low traffic.
Getting accepted into ReviewMe is easier than other sponsored review websites. You can try signing up at ReviewMe immediately after setting up your blog and having a few posts there.
Cons
One major defect of ReviewMe is that they offer reviews from a niche advertiser market. There review offers tend to repeat over months, that you maybe in danger of writing reviews for same site again and again which can harm your blog seriously.
Offers from ReviewMe, though they claim will give you at least 20$, often starts at 5$ for 200 words which can often be a hard bargain for some bloggers.
Once in a while after you accept a review; it may get cancelled by an advertiser, which can cause enough frustration for you. Only bloggers know the work they put in behind writing their opinions about a particular website.
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Overall though, ReviewMe can be a good source of income from blog, if your blog has decent traffic. Though if your blog has great search engine rankings and exponential traffic rise, in the tune of around 600 hits per day, you can get very high review offers at ReviewMe to the tune of 100 bucks and more per review.
If you are just starting up and want to earn some money from your blog, ReviewMe is a good choice for you.
Check more about it at ReviewMe.com or
Know More and sign up for ReviewMe here:

It is not a referral link. ;)