Here are some outside links that may be of interest or help. If you would like to suggest others please let me know.
Some sites dealing with interventions:
The Surveillance Camera Players. These guys have been acting out in front of surveillance cameras since 1996!
How to Respond to an Emergency. This remarkable event in Toronto also used Argentine Tango as a public intervention.
Woody’s Ghost. Preston Poe’s Jug Band Interventions were the inspiration for me to start doing Tango Interventions. This is a link to his 2008 intervention series during Conflux Festival.
And speaking of Conflux Festival, you will find a plethora of interesting interventionary actions at their archive from the 2008 festival.
More specifically related to tango in unexpected public venues, here are some links to tango flashmob events from as early as 2003:
Here are some sites having to do with surveillance: