You can select any Foursquare contact and declare him or her “dead to you.” And that’s just a start – you can also insult some person, picking from a list that includes such things as “jerk,” “cancer” or “douchelord.” It’s hilarious.
I’m not a big fan of Foursquare, but I can clearly see how it (and other location-based social networks for that matter) can be useful. Moreover, I’ve no doubts that “Please Rob Me” and Avoidr are just the beginning, and we’ll definitely see more cool (and non-cool) things being made by third-party developers. In the meantime, feel free to insult me on Foursquare.
(Actually you can’t cause I’m not using it).
And finally, it’s also interesting to put Avoidr in the other perspective — whenever someone creates a service for friending people online, a new, completely opposite service emerges. Hatebook is probably the best example…