Amit Singhal, a Google fellow, who heads their search team and essentially rewrote the critical ranking algorithm in 2001, and a graduate of IIT Roorkee [1];
Sundar Pichai, who heads Android, Chrome/Chrome OS, and Google Apps [2] - a graduate of IIT Kharagpur;
Vic Gundotra - who heads Google+ and social and is a graduate of IIT Bombay [3];
Nikesh Arora, who is Google's Chief Business Officer, a graduate of IIT Varanasi [4];
Sridhar Ramasway - SVP for Ads & Commerce - a graduate of IIT Madras [5], plus dozens of other key people.
(The latter two are listed on Google's management team page at : http://www.google.com/about/company/facts/management/ )
Not to make too fine a point about it - but IMHO Google is one example of the influence and impact of IITians on the world.
[1] http://en.wikipedia.org/wiki/Amit_Singhal
[2] http://en.wikipedia.org/wiki/Sundar_Pichai
[3] http://en.wikipedia.org/wiki/Vic_Gundotra
[4] http://en.wikipedia.org/wiki/Nikesh_Arora
[5] http://www.linkedin.com/pub/sridhar-ramaswamy/2/220/972
Edit: Formatting