Digitizer Tool, Google maps KML/Poly tool: http://www.birdtheme.org/useful/googletool.html 

Marker, KML tool: http://www.birdtheme.org/useful/markertool.html

Free Topography tools: http://freegeographytools.com/

KMLxL / Modify KML with Excel: http://freegeographytools.com/2008/modify-a-kml-polygon-file-with-excel-data 

BING Maps Lat/Long Finder: http://www.doogal.co.uk/VELatLong.php

Embed Map tool / Google Maps: http://freegeographytools.com/2008/simple-online-form-for-creating-an-embeddable-google-map 

CSV->KML: http://www.tothepc.com/archives/convert-csv-to-google-maps-kml-file/  (Java)

KML->CSV->KML: http://choonchernlim.com/kmlcsv/ (Java)

JSON->XML: http://www.thomasfrank.se/xml_to_json.html

http://goessner.net/download/prj/jsonxml/ (JavaScript)

http://json.codeplex.com/ (.NET)

Simple Geocoder: http://route4me.com/public_geocoder.php  (support batch CSV up and down)

Batch Geocode on a map (free doesn't seem to have lat/lon): http://www.batchgeo.com

http://freegeographytools.com/2010/convert-an-excel-address-spreadsheet-into-a-kml-file-and-then-into-a-geocoded-csv-text-file-with-kmlgeocode-and-kmlreport

http://freegeographytools.com/2008/geocode-a-google-docs-spreadsheet-and-plot-it-in-google-mapsearth-with-map-a-list

Great example for lots of map-related (incl geocoding): http://econym.org.uk/gmap/index.htm (google maps) Batch geocoding: http://econym.org.uk/gmap/geomulti.htm

BING API Geocoding sample: http://www.bing.com/community/site_blogs/b/maps/archive/2010/08/31/batch-geocoding-and-batch-reverse-geocoding-with-bing-maps.aspx

Method: http://msdn.microsoft.com/en-us/library/cc966817.aspx

GPS visualizer: http://www.gpsvisualizer.com/

Calculate lat/lon for a specific direction & distance from a point: http://www.movable-type.co.uk/scripts/latlong-vincenty-direct.html 

Same as above, but math: http://mathforum.org/library/drmath/view/52049.html 

Heatmaps: http://www.jjguy.com/heatmap/ (Python)

http://www.viksoe.dk/code/heatmap.htm (C#)

http://www.labsmedia.com/clickheat/156914.html (PHP)