I recently had the need for some GIS features on a project. As the project's budget didn't anticipate a commercial GIS tool, I asked for an advice to the GIS experts: the answer was MapWindow GIS.
I was impressed by the quality and integration ease. We used the shapes and DBF databases from a well known (and costly) commercial tool and customized some interactive GIS views in a couple of days.
Unfortunately I can't show you the views, so here's a map from MapWindows GIS: