Lifehacker today suggests you try Gizmo, an Internet phone with a handy feature for freelancers: "One nice feature of Gizmo is that it can record conversations. In order to avoid misuse or confusion, a voice on the system says “recording conversation” — a message the other party hears as well — gizmorecording.jpg when you press the record button. When you are done, press the red button and you have an archive of the discussion - great for podcasts or interviews or just chatting with your 3 year old niece." And it's free.

If you're looking on additional advice on choosing a digital recorder, Lifehacker has advice here and here.