I'm beginnning posting some basic software I've written at sourceforge. However, I read over the GPL, and was slightly concerned that someone could charge a fee for distributing the software.

I was wondering, is there a license out there that ensures that the software remains free of charge, so that no one who downloads it can sell it, but can only redistribute it for free?

Thanks!

The GPL only allows a fee for distribution of source code, it's not mandatory. Put it this way, if I charge $5 to allow for postage and the cost of a blank CD and you allow people to download it free of charge, who will users go with? It's all down to what the market will bear.

No one gets rich from selling GPL stuff unless they can make and distribute it in large enough volumes to offset their costs. If the licence does everything else that you need, I would see this as a very minor thing.

If one person charges for distributing GPL software source, then you have to bear in mind that anyone else is not bound to charge the same amount. There's nothing to stop one person buying the source from you and then making it freely available themselves; this is basically what CentOS does with Red Hat. And in the current climate, there's far more money in software support than in sales anyway, so this is not currently a major issue.

If the GPL doesn't fit your needs, then there are plenty of free software licences available. a good place to start looking is http://www.fsf.org/licensing/.

Be careful, though: a software license is a legal document, so you should always be careful which one you choose. The GPL has been designed by lawyers and has been challenged in courts of law but never successfully, which gives it a strength of legal precedent in some countries. There are also a lot of other licences out there that have never been challenged in a court, and so may have gaping loopholes that the average user may miss, or may simply be unenforceable. If in doubt, ask a software lawyer.

Since fast internet it's not something to worry about - there used to be CDs that were sold that contained freeware and shareware game and demos of games and they always had at least a 100 of those and they made some interface to browse through them but those times are over (although they are nice to remember old games back when buying those you had to send 5 bucks via mail...)
The GPL should cover you but real life gets in the way - you'll need to find a way of searching for compiled versions of your source code to see if the GPL is being violated.

Debian