In Europe, gliders and general aviation including helos often use FLARM.
One of the genuinely useful aspects of FLARM is that it has obstacle databases for Austria, Italy, France, Switzerland, Germany (UK where are you?) which has reduced the incidence of aircraft striking cableways in the Alps.
FLARMs are cheap -- about 500 GBP. Had a FLARM been on the crane and the helo, it would have received a timely warning.
Flarm - Homepage
Here in Canada, PowerFlarm has come out. So far I've found it quite handy detecting gliders hiding directly underneath me in the same thermal.