Best of the Web
This site includes a huge selection of Donne's most poems, sermons, and essays, all of which are brilliant.
The Foundation's website has the best long biography of Donne available online.
The link to the audio is at the top of the page.
A site with audio readings of some of Donne's more famous poems.
A more official-looking portrait of Donne.
The famous image of melting clocks, painted by Salvador Dali, seems fitting with this poem.
Donne was both a worldly poet who celebrated love and sexuality, and also a reformed Catholic priest. This biography attempts to reconcile these two aspects of his life.
If you really want to be a John Donne scholar, you should get your hands on this multi-volume edition of his collected works. It's the authoritative version.