You can start using Roamler right away, unless you live in a region where there are enough Roamlers already. Register in the app by using the link 'Click here to register' and be part of the mobile workforce! You can find more information at http://blog.roamler.co.uk/?page_id=589 on how to register.
With Roamler you can complete different tasks for all kinds of brands. You might be asked to take a picture for a brand that wants to know how their product is displayed in different spots, you could be exploring the city to capture the best graffiti art, answer questions about an advert at the bus stop near you or show brands how you use their product at home. The more Experience Points (XP) you have earned the higher level you gain and the more interesting tasks become.
Roamler presents you with a list of tasks (also displayed on a map) based on your location. Accept and perform the task and send Roamler the results. After verification, the brand gets the answer and you receive your XP and money.
Note that continued use of location based services running in the background may decrease battery life.