This free online converter will translate an AutoCAD file (in DXF or DWG format) to a shapefile or KML format. It can also convert from KML format to shapefile, or KML to DXF, or Shapefile to DXF. Choose the output format you desire and select your input file, then press Convert File.
This converter is based on open source components, and source code is available via the IBM developerWorks article on this topic. (The bulk converter below is based on different tools.)
DWG note: DWG 2000 format files will work best, but in general DXF is a better format for data exchange. If at all possible use DXF files rather than DWG files for best results.
If the simple tool above is insufficient for your needs, consider the Bulk DXF to Shapefile Converter. This tool will allow you to convert one or more AutoCAD DXF files into shapefiles in one pass. Note that this converter does not support DWG, only DXF. Each individual DXF file is converted into four files: one for each geometry type, and one for text. For example, if you convert c:\data\test.dxf, your output files will consist of...
In addition to geometry, the DXF layer names are preserved as an attribute table field. Any custom coloring or thicknesses are also stored as attributes, and any label rotation is saved in the -text.shp attribute table. The desktop version can also handle more complex entities such as LWPOLYLINE bulge values.
The converter includes a GUI (Graphical User Interface) allowing you to select multiple files for batch conversion, or you can pass a single filename to it via command line, useful for use with other tools, scripts, or batch processes.
GPX is a common export format for GPS data loggers (including mobile phone apps).
Are none of the above tools meeting your needs? Contact me for a free quote on a custom data conversion tool or project.