He is the founder of an organization that has offices in six countries; has travelled and spoken in dozens of countries, including Cambodia before it fell; this ministry has spanned 30 years; RZIM has a budget of over $5,000,000/year; was a visiting scholar at Cambridge University; current visiting professor and senior research fellow at Wycliff Hall at Oxford university; has spoken at such ivy league universities as Harvard and Princeton; has spoken twice at the National Prayer Breakfast at the United Nations (a mainstream venue); also spoken at the National Day of Prayer in Washington, DC; his speaking at the Mormon Temple was the first time an evangelical Christian has been allowed there since D.L. Moody one hundred years ago; he has a radio program that airs on over 1500 stations worldwide; has also spoken at Lenin Military Academy in Moscow (largely atheist at the time, not sympathetic to Christianity); has authored over 20 books, published by such respectable houses as Zondervan and Multnomah, and including Can Man Live Without God which won the Golden Medalion.  I think all these things add to the case of Ravi Zacharias' notability.