Are there any services that allow you to place advertising in Windows software? I want to give away my software for free but still need to eat!
It is, of course, trivial to put a fixed collection of adverts into your code. The trouble comes if you want to sell eyeballs and have the ads change. Then the code has to go talk over the network to get new adds.
Many people would have a name for this: adware. If people find you making network connections behind their back, as it were, they are likely to break out some more negative terms.
However, if you are completely open and honest about it when you offer the code for download, then your conscience might be clear.
Practically, you need to have code that makes a network connection to some site of yours, pulls the ad content, and displays it in some sort of annoying popup.
Check with individual affiliate programs to see if they allow links in applications.
You can also try the Freemium model: Turn on some extra features if they pay for your program.
Or link to your website for support information, instructions, etc., and place ads there.
Or offer an e-mail newsletter with updates, news, etc. Advertising in these is easier.
You can also ask this over at http://www.startups.com