There's an extensive discography here. Unfortunately, it doesn't tell you which recordings are currently available.

AMG/All Music Guide is a good source of information. Type "Ewan MacColl" into the search box, and it will bring up a biography and a list of recordings. The ones with a red "buy" button in front of them are the ones that are currently for sale, at least in the US.

Another good source of information about current CDs is Yahoo! Music. I especially like it because it has lots of sound samples.