Devshed is doing it pretty effectively with their Plug-in Magazine! But maybe that's because they are a pretty huge brand and have connections or perhaps they are in tech market where the advertisers understand the digital opportunities!

This is by no means to discourage you but you are gonna have to do some training for advertisers You would have to give them in detail the pros and cons of actually advertising in digital magazines and why it is better than / as good as advertising on sites and PPC Search engines!

Good luck with your venture