PoetrySoup.com : It has a large active community of poets, many member sponsored contests and a site sponsored contest, also. Great place to connect with poets, try out different forms (many you many never have heard of before).
Allpoetry.com : Good place to meet friends and post poems
Goodreads.com : everyone has a blog associated with their bookshelves, use it to write poems and join the poetry group to make friends.