If you're a gardener or farmer- these little guys should be on your radar. They are insectivores: ravenous consumers of pest insects galore. On the wing, they are acrobatic hunters- taking out flying insects and gleaning from leaves and plants.
There are 3 species of phoebe in the US- the black phoebe, the Say's phoebe, and the eastern phoebe:
[Side Note: As part of my PhD research, I found that New Zealand falcons brought more food to larger broods, but the chicks that had siblings got less food overall than single falcon chicks.]
If you want to encourage more phoebe's around your property (and everyone should!), keeping waterways flowing and surrounded by natural vegetation is key. Count yourself lucky if you spot a cup-nest made from mud and mosses in the corner of your garage or under an eave at your house- a phoebe nest will give you hours of entertainment as you watch the parents tend to their 2 broods each summer (but be sure to keep your distance), and just think of the pest control services that one pair of Phoebes will give you over the course of a year!
Wolf, Blair O. 1997. Black Phoebe (Sayornis nigricans), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/268
All About Birds for Black Phoebe, Say's Phoebe, and Eastern Phoebe
The website of the Hauber Lab
Croston, R. & Hauber, M. E. (2012) The Ecology of Avian Brood Parasitism. Nature Education Knowledge 3(10):56