CoupleVIBE (Bales et al 2011)
"In CoupleVIBE, when a user arrives at or departs from a frequented location, her partner automatically receives a vibrotactile message on his mobile phone [...] CoupleVIBE's visual interface is basic, consisting of just two screens, the status screen and the vibration assignment screen. A user tags a location [... and] is asked to give a name to the location [...] the user's partner selects a vibrotactile message to identify the location.
Reference: Bales, E. et al. 2011 CoupleVIBE: Mobile Implicit Communication to Improve Awareness for (Long-Distance) Couples. In CSCW 2011