Programming languages: python, javascript. Frameworks: tornado, django, jquery, angularjs. Data transmission: websockets, ajax, json-rpc, xml. Geolocation API: google maps, yandex maps, osm, openlayers. DB: sql: mysql, postgresql, sqlite; google bigtable. VCS: git, mercurial, svn. Bug tracking system: jira, redmine, trac. Other: Linux, google app engine, memcache.