This feature would mark certain phone numbers as "sensitive" and would ask you to do a CAPTCHA style test (or enter some extra confirmation that random body parts can't provide) before dialing certain numbers.
A fancier addition might be time zones and "do not disturb" times associated with certain numbers which might come in handy while traveling (e.g., "it is 3am for restricted contact Mr. Huntington III -- are you sure you wish to proceed?")
As it is, I am afraid to enter certain people into my contact list, lest I accidentally dial them at 3am...-- cowtamer, Jan 19 2011 Having accidentally awakened the wrong people at the wrong time, I want some numbers to just be difficult to dial :)-- cowtamer, Jan 20 2011 Hmmm. The phone should be able to figure out the time it is at the number you just dialed--my (non-smart)phone has a world clock and tells me the name of the (American) state of the caller, so combining the two isn't hard. The phone could then say, "It is 4:00 o'clock in the frickin' morning there, are you sure you want to complete this call? For yes, press 666. For no, press any other button or shriek in fear."
When programming numbers in your speed dial, there could easily be an option for Business Hours Only, Waking Hours Only, or Drunken Bastard.
Which could easily lead to taking calls from those numbers only at selected times.-- baconbrain, Jan 20 2011 random, halfbakery