The company I work for is a pay-for-subscription news website. Is it legal to use Quantum GIS (QGIS) to host maps that would be only available on our site to paying subscribers? I'm having trouble figuring out the GNU license. Any help would be appreciated. Thanks.
You can use it for everything you want - no restrictions apply.
You also can sell QGIS itself (you just need to find someone who's willing to pay).
But if you do (even when you distribute without charge), you have to include the source code of QGIS and all own extensions (plugins, features, whatever) you added. Basically pass on everything you got (and not restricting it by anything you add).
For more general GPL questions checkout http://www.gnu.org/licenses/gpl-faq.html.
I had been using ArcGIS but due to requiring a more expensive license there were certain operations I could not do. Quantum was able to do the operations at no cost. Qantum is a great bit of kit