Any Question Answered (AQA), and Ask118 are internet businesses often on the lookout for researchers. All the companies work the same way: a customer searching for the answer to any random question sends a text to researchers - you - who replies with the answer.
The beauty of this work is that you can choose the type of questions that you answer, and hence the hours you work. See Issuebits (AQA), and 118 for vacancies - you'll likely have to pass a test before you get an interview. Vacancies aren't open all the time, so you'll need to be on the ball and checking the sites regularly.
How much? You'll be paid roughly 30p per question, and some can take just a few moments to answer, meaning that experienced researchers get up to £2,000 a month.