I use a range of different GIS software, both free and commercial. I also try and keep the pulse of free downloadable GIS tools that help me do my job without breaking the bank (Mapz mentions several great ones).
A couple years ago, I was turned on to Accuglobe by DDTI and was incredibly impressed. With DDTI’s Accuglobe (and grants from AT&T and IEDC), we in Indiana have been able to freely distribute our statewide IndianaMap 2005 Orthophotography data with over 70 other data sets bundled with free software to over 200 Indiana public libraries and economic development organizations (with the grant assistance, we provided training too!). Now the DDTI team has released their completely rebuilt 2007 version – and it rocks. It has a new look and feel (OK, I haven’t quite gotten used to it yet) and greatly improved features, including Open Web Map Service (WMS) functionality and a Pictometry viewer that I haven’t used. It can also now handle on-the-fly reprojection of shapefiles – a blessing for regional or statewide applications using data from multiple projections. I am particularly excited about the WMS capability – we have several map services running huge databases (did I mention our statewide orthophotography project?) and now users can stream in the whole state to a free desktop application. Check this one out. Go to www.ddti.net to download and give it a whirl.