I prefer the Free Eagles app for Android - the Surveys are (so far) clean and guaranteed to drop a minimum of at least 2 GE thanks to how the system handles it, even if you just bum-rush through the answers with [email protected] information.
The handler also has a time multiplier - the longer you spend, the more you get (each has a specific cap however), so open one while you're climbing 20,000ft then finish the survey - boom, 26 GE for spending 10 minutes on a 2 minute survey.

note: I have received 105 GE from a single 25 minute survey (k-ching)

There are also various games you can install and usually require you to reach a certain level in them (like complete a tutorial, reach level 10 etc) and take roughly 10-30 minutes to do.
Some just want you to download and open, nothing else.

There's also an invite system that allows you to net 20% of anything the person using your code earns.

This is my code: (ﾉ◕ヮ◕)ﾉ*:･ﾟ✧ sfb9a

...if anyone wants it (you'll get 10 GE right off the bat)

Oh and you get to open 1 chest every day for free with the chance of winning 300.