Andrew Cram's website
http://www.andrewcram.com/frequentflyer1.html
was last updated August 19, 2004, but it definitely isn't down--I just used it last night. Though it doesn't have anything about the current mileage shopping bonuses (i.e., American's AAdvantage eShopping bonus, etc.), it is incredibly comprehensive in listing sites and the standard mileage offerings from all sorts of airlines, Gold Points, etc.