I find it terribly annoying whenever someone calls and I just don’t know the number. Reverse Phone Lookups aren’t usually free and even though it’d be incredibly useful for a lot of people, their high fees tend to put them off.
Anyway, there’s a great alternative to paid services. FindOutWhosCalling.com is a free service and even includes a National No Call Registry.
You can run a reverse phone lookup without being charged. Great site.