They've also been featured on I Can Haz Cheezburger:
Tarsiers are small, nocturnal primates whose 4-7 species live in the islands of Southeast Asia, including Indonesia and the Philippines. Trademarks of their appearance are enormous eyes (which can outsize their brains), long feet (which give them their name--their tarsus [ankle] bones are extremely elongated), and long, spindly fingers.
Photo source: That's Just Ugly
Tarsiers possess an abundance of exceptional traits. They can rotate their necks 180 degrees in either direction. They are the world's most carnivorous primate, exclusively eating live animals that include insects, snakes and other reptiles, amphibians, and even birds. They are primarily insectivorous.
They give birth to giant babies that can weigh 25-30% of the mother's weight (imagine a >30 pound human newborn!). According to Tarsiers: Past, Present, and Future, "Since infants are so heavy, mothers and other group members rarely transport them. Instead, a mother will park her infant on branches while she forages nearby."
Photo uploaded by flickr user Specklet
As if all this weren't enough, tarsiers have incited a raging century-long debate over their proper phylogeny, or relationship to other primates. Some argue that their morphology shows their close relatedness to strepsirrhine primates (e.g. lemurs, lorises, and bush babies). Another camp scoffs at such absurdity and cites genetic, anatomical, and reproductive traits that make them haplorrhine primates (e.g. monkeys, apes, and humans).
Their ugliness factor also remains controversial; I personally find them to be utterly adorable, but, incredibly, others have ranked them the world's fourth ugliest animal.