Skype.

Users: 90,033 Computers: 71,225 Different versions: 1   Total Keys: 7,058,820,965 Total Clicks: 767,826,739 Total Usage: 632 years, 17 weeks, 6 days, 1 hour, 13 minutes, 59 seconds   Average Usage: 2 days, 13 hours, 31 minutes, 32 seconds