Also you want to make sure the ratio between different language speakers is well balanced. I can see the reason behind a lot a Brazilians and Hispanics wanting to learn English, it's the most important language after all. But are there as many English speakers (mostly Americans) who want to learn Spanish and Portuguese? What are the motivations for them to pick up a second language?
No, from my experience with sharedtalk this is a definite problem for certain language learners (although not necessarily the startup since they don't need to appeal to everybody). Native speakers of English are in demand from native speakers of almost all languages. If you are a native speaker of a language popular with English speakers (such as Spanish or French) and want to learn English you are also in luck. However, on sharedtalk there are often many speakers of certain languages (such as Turkish and Chinese) wanted to learn English whilst the reverse is not true, and if, for example, you are a Turkish speaker wanted to learn Czech then your chances of finding a suitable exchange partner are very slim indeed.
The speakers on sharedtalk also vary with the time of day, so it helps if your timezone is similar to that of the countries which speak the language you wish to learn.
