This site has a huge amount of information–full texts of poems, articles and essays, and a searchable database (search by poet, title, subject, keywords, etc).
Another site that has a ton of different kinds of poets and poems (both contemporary and more traditional). The search features are a little less flexible than the Poetry Foundation’s.
This site is devoted to much more contemporary and experimental writers.
This site has full texts of many out of print contemporary poetry books.
A site devoted to recordings of readings and talks by writers old and new.