You would have to know what that problem is though. You sure don't want to guess. Just make sure the information is something that will be of use to them whether it is a solution to a current problem or not.
It depends on what your site is, but there are a lot of things you can try like eBooks, short reports, wallpapers for PCs, if it is an image site free images. etc. Just try and find something that will appeal to your audience.