The three that are out there (as of this writing, these are the only three), are Appen-Butler Hill (APH), Leapforce and Lionbridge. I am a 'researchaholic' and as a result, spent a lot of time looking into this opportunity. It seems ABH and Lionbridge are better liked than Leapforce and this is consistent across many different message boards.
With that said, I need to be a little careful in what I disclose because I have taken the prescreen test for ABH and am waiting for additional qualification tests to take with them. In the meantime, I was offered the chance to take the test with both Lionbridge and Leapforce and all of these companies have strict confidentiality clauses. The information I provide is what anyone can get from searching online. The three companies' pay structure is similar and if you inquire further, they do tell you how much you can expect to earn. The pay is roughly $12.50-14/hour, you would be an Independent contractor and you can only choose one company to work with.
Speaking of testing, ABH's testing process works a little differently than the other two. After you apply you may be offered the chance to take an online test (prescreen) that uses different methods of testing (ie math, analytical, reading comprehension etc). After passing this test you are eligible to continue with the testing process. There seems to be a wait time between taking the prescreen and continuing with the qualification process. I am still waiting and I took the prescreen a couple weeks ago. While you are waiting to qualify further, it is possible they will offer you a short term project that is not related to search engine evaluating. I was offered a short term project but I really do not have the time right now to take on any more. I do not know if it is commonplace for ABH to offer these small projects or if this was a rare opportunity.
If you need income very quickly, the qualification process may be too long with ABH but the feedback I have read has been positive for ABH and they are my first choice in search engine evaluation companies. I just read on a forum that it can take days, weeks or months waiting for to take the final qualifications.
Although ABH is my first choice, if I take the test with Lionbridge and pass, I will work with them. Lionbridge and Leapforce have similar tests (ABH may have the same test set-up when it gets time to the final qualification but since I am not there yet, I do not know for sure). If you want to test for either of the 'L' companies, be prepared to take time out of your schedule to study. They suggest 10-12 hours of study time and judging from the study manual, I can see why they say that.
Regarding Lionbridge, I received the testing information on Oct 5 and had five days in which to study and take the test. I procrastinated and before I knew it, Wed was here and I did not study. I was bummed that I had a chance to work with them and make some decent money but today in my inbox was a message that they are willing to let me take it one more time. If I choose to not take the test this time, then I will receive no more chances. This tells me they are in need of people for this type of work and I have vowed to actually study this time and take the test.
If you contract with Lionbridge you will be between 10-20 hours per week. Unless it is a special 'bonus time', no one is allowed to exceed the 20 hour maximum limit.
Leapforce was the first company to offer me to take the test and I had the best of intentions. I printed out the entire study manual (165 pages) but I kept putting off studying. This went on for a couple weeks and Leapforce extended the opportunity to take the exam again but instead of only giving me one chance, they have given me 4 or 5. I am unsure if they will yet again offer the chance to take the exam but I will take it if they do. I do not know if it is because Leapforce has the highest number of evaluators or what but they do get a lot of negative feedback. I have read that most evaluators do not make it beyond 60 days but if you make it beyond 60, you will most likely be a long term evaluator. The reasons I have heard for this range from “no feedback”, “no communication” “they fire you with no explanation” as well as “the test is so different from what happens in the real world that people get frustrated and quit”. Of course YMMV as I have read some posts that defend Leapforce.
There is a reason the pay is higher than most work at home jobs and I suspect it is because this type of work is not easy. You have to be exact and fast with excellent problem solving skills. Even though my ADHD gets the best of me, I think I could do this as I have a tendency to 'hyper-focus' when I am really into a topic. I can literally get lost in time and before I know it, two hours has went by.
I will keep the blog updated on my progress, how the test went for Lionbridge (because I will be studying, I will take the test darnit).
There is more information online regarding this type of work and this WAHM.com forum has a lot of information as well.