Image of Austin Neighborhoods: http://1.bp.blogspot.com/-E7lbrj60fas/T7LM6oc-rGI/AAAAAAAACE8/msEC7SbhubI/s1600/Compressed+24x36+Austin+Neighborhood+Map+4.23.12.jpg
GeoJSON editor: http://blog.sallarp.com/geojson-google-maps-editor.html (uses google maps)
Another GeoJSON editor: http://macwright.org/edit-geojson/ (accepts custom code and loads overlays)