So far I have been slowly and steadily been filling out surveys for different sites (examples here) which have now accumulated to a respectable amount.
It is not much compared to other sites and not as reliable since you do not know beforehand how many surveys you will be able to fill out and what they will pay but still enough to make it worthwhile.
My total earnings are thus far: $168,62 from surveys, averaging $1 per 4th minute, or $14 per hour. Now during the summer I am seeing a decline in surveys available which is to be expected.
The good thing about surveys is that you can choose yourself when you want to fill it in. You can do it while some other site you frequent is low on money making opportunities or while doing something else.