First and foremost, here it is being read by the man himself:
The Wikipedia page on Prufrock is very thorough
The Hypertext edition helps in tracking down allusions etc.
Excellent study guide on Prufrock
A classic text is Ezra Pound's review of Prufrock and Other Observations (1917) in Poetry,Vol. 10, No. 5 (Aug., 1917), pp. 264-271. Also available here.