Smart Tags offers a good way to extend Dynamics GP beyond your GP-user base. Access to the information can be easily secured using Windows security, and there is no additional licensing required.
My previous post discusses some of the basic functionality of Smart Tags, from the user's standpoint.
The Microsoft Office Smart Tag Manager for Microsoft Dynamics GP 10.0 page is a good place to start if you want to try it out.
I put together this little video to show you how easy it is to install and setup.
If you're not using Smart Tags, you should at least try it out and see if your non-GP users like it.