Merriam-Webster's Word of the Day for April 20, 2012 is:

gregarious • \grih-GAIR-ee-us\  • adjective
1 a : tending to associate with others of one's kind : social b : marked by or indicating a liking for companionship: sociable c : of or relating to a social group 2 a a of a plant : growing in a cluster or a colony b : living in contiguous nests but not forming a true colony — used especially of wasps and bees

Examples:
My travel companion is a gregarious soul who makes friends easily, so we never want for company at dinner time.

"Mr. Dean, who is also an ordained minister and a voluntary Chaplain for New York City Transit, is known for his gregarious, welcoming attitude on the job."— From an article by David Sims in The Chief-Leader, March 19, 2012

Did you know?
When you're one of the herd, it's tough to avoid being social. The etymology of "gregarious" reflects the social nature of the flock; in fact, the word grew out of the Latin noun "grex," meaning "herd" or "flock." When it first began appearing in English texts in the 17th century, "gregarious" was applied mainly to animals, but by the 18th century it was being used for social human beings as well. By the way, "grex" gave English a whole flock of other words too, including "egregious," "aggregate," "congregate," and "segregate."