Websites
Don't worry, there's an app for that. (Or at least a Facebook page.) We're card-carrying members. You should be, too.
The Academy of American Poets runs a pretty tight ship, so when they include info about a poet, you know it's good stuff. Check out their site, which includes bios on Auden and Yeats, a bunch of poems, and even some recordings.
Here's the BBC's version of Auden's bio, along with extensive links to all things Auden.
Check out the Norton Anthology's website for some commentary on "In Memory of W.B. Yeats."
Video
Check out this interview with Auden. He briefly discusses "In Memory of W.B. Yeats."
Audio
Listen to Auden read "In Memory of W.B. Yeats."
This reading is quite different than Auden's. This guy sounds awfully depressed.
Documents
Want to read a non-poetic tribute to Yeats? Check out his obituary in the NY Times. How is this obituary different from Auden's poem?
This one is from the Guardian.
Images
Auden looks like a man who did some hard livin'. You can scope him out here.
Here's a picture of Yeats.
Books
You could think of this as an Auden master class: it's got all of his major works in their final form. Get a preview on Google Books.