What's worse is that the papers ACM charge for via their Portal site are often papers you can get (legally) for free elsewhere.

For example, there is an ACM Portal page ( http://portal.acm.org/citation.cfm?id=1553489 ) for a paper I wrote that is freely available from the conference site ( http://machinelearning.org/archive/icml2009/abstracts.html ).

There is no indication on the ACM page (the DOI on that page just returns the ACM page) that this content is available elsewhere without the $15 fee.

It's bordering on unscrupulous in my opinion.