Sorry, I meant to mention MP3.com.

But if you want to get into traditional repertoire, you have to specify what tradition! Fairport and Steeleye and their (dozens of) personnel over the decades have amassed a pretty fair discography of English/Scottish folk tradition--particularly Martin Carthy and Maddy Prior (June Tabor? she must have done a spell with one of em, mustn't she?). And look for recordings by The Copper Family, Jeannie Robertson, Archie Fisher, Ray Fisher, Cilla Fisher & Artie Tresize, Ewan MacColl, early Dick Gaughan (No More Forever). Quite a bias towards Scottish singers there since that's what I know (I'm a Cameron fer godsakes).

What makes it worthwhile to search out these folks' recordings is that you will get the standards and quite a bit more, which is where the fun starts IMHO.

Best of luck

Willie-O