Best Free Arizona Map: Check out GPSFileDepot for a free Garmin Mapsource 24k quality topo map of Arizona.  The map has better shaded relief detail than Garmin's Topo series maps; however I did find a projection problem generating a 20ft due south drift in the Tucson city proper area verified with my GPS and Garmin's Navigator.

Best Free Government Map: Sabino Canyon. This isn't the Cadillac of maps, but it does get the job done.  It contains the major trails, picnic and tram stop areas and a general sense for the topography. Sadly the state and federal governements don't produce very goof online, free maps but they are willing to sell you one at every station.

Best Free Non-Government Map: HikeArizona.  As you can tell from my Trails page, I like what HikeArizona has been doing.  The map created of the Catalina Mountain trails is an excellent pictorial.  It may not be highlt detailed but it puts to shame the Coronado National Forest online map.

Best Source for Map Tiles:  This is a toss up.  I like the Univeristy of Arizona's ARIA site for its mixture of DRG, Landsat, DOQQ and NED information, but the site can be unreliable at times. I also like GeoCommunity. This site takes USGS public domain information and organizes it for either free or premium download speeds.

Best Source for Arizona GIS data:  Pima County DOT GIS. This site is only for the Pima county area, but its wealth of different datasets makes it one of my favorites.  Here you will find census, zoning, flood, habitat and many other GID data from multiple government agencies.  The only bad news is to access some of the data you need to submit a request to access their ftp site.

Best Commercial Mapping Software for Arizona:  This is tough and probably my most controversial pick.  I like Maptech Navigator because its tools are everything I need to create and view multiple layers of data such as tracks, waypoints, geopins.  It is also very accurate and operates very stable.  I do have some wish list items such as the txf format retaining elevation data, but overall this is a great package.

Best Commercial GPS Trip Planning Software for Arizona:  I am partial to Garmin products so I recommend Garmin Mapsource with City Navigator and Topo 24K.  This software is very simple to use and because of Garmin's market share it is easy to find support and tools to go along with it.  If you GPS is another brand you may find a better mate such as Delorme.  This recommendation only considers GPS handhelds and ignores car GPS software which is a different beast.

Best Hiking GPS Unit:  I hesitate to name just one since everyone is always passionate about the one they just spent $500 on; however, I personally like the Garmin GPSMAP 60Cx and the Delorme Earthmate PN-20.  Both are reasonably priced, have a highly accurate receiver, and good screens.  The only downside with the 60Cx is that it doesn't use titanium batteries until slightly drained (brand new titaniums create over-voltage issues).  This may seem a little old fashioned considering that the Garmin Oregon just came out, and I suspect that a next generation of touch pad/iphone style units will be rolled out soon, but on the flip side I am beginning to also question the manufacturer's unit testing and quality as GPS units are becoming more a commodity and ubiquitous.  The Oregon for instance has a lesser chip receiver (see review)and the Colorado was initially plagued with a few firmware bugs (see review).  What is important in a hiking GPS never changes:  good battery life, water resistant, shock resistant, and a good receiver.  Everything else is fluff.

Best Free Mapping Software:  The obvious and popular choice is GoogleEarth.  The interface is one of the best: lots of cool factor.  The kml/kmz format has also begun to standardize communication between the proprietary formats of all the commercial mapping vendors' formats.  ESRI, Microsoft, TerraServer and others have tried to answer with simliar offerings but not to Google's success.  My runner-up is a little known app called 3DEM written by Richard Horne that requires you to download tilesets, but is very effective.

Best Free Trip Planning Software: Coming Soon.

Best GPS Data Conversion Tool: I used to use g7toWin a lot and I still like the completeness of tools that it offers. However the Google kml format has made conversion issues less important to me, and GPSBabelGUI  with its more straight forward (and less robust) interface usually takes care of what I need.