The first is the excellent MP3 Skype recorder. This free bit of software does exactly what its name implies and records a conversation of any length to your hard drive in a quality that is good enough to transcribe (you can up the quality if you'd like, but you don't need to, the default is perfectly fine). Now all I need is automatic transcription software that's free and works... :D
The second is perhaps even better. Ring2Skype gives you a real phone number in over 100 cities in the world and you can have as many as you like for nothing. The phone number costs you nothing and it means that your contacts should only have to pay for a local phone call to get to you, cutting down their costs too. In combination with the MP3 recorder it makes a perfect duo for journalists.