Should I work for free?
shouldiworkforfree.com
shouldiworkforfree.com
Of course, in a few cases on there, you ARE getting something for your hard work (or repaying favors you already got), it's just not cold, hard cash.
Any trade that isn't in balance is bad for both sides. It may not be immediate, but it will be eventually.
Think about all those open source projects on GitHub - if nobody ever worked "for free", you would get such great wonderful projects like some amazing jquery pluggins and what not.
I think when people think in a small short term view like this, they severely limit themselves.
I definitely do technical things for free, but I'm free to walk away any time -- I think the essence of "work" is the inability to walk away (without terminating whatever contract is in place).