Hi HN, I just launched SaveThatCall, which allows users to record and download phone calls in MP3 format. I built it after having a personal need to download a recorded voicemail message and finding no easy and inexpensive way of doing it.
http://www.savethatcall.com
It is built using Google App Engine and Twilio, with payment processing through PayPal and some audio file work done with a Python script running as a daemon on Dreamhost.
Your feedback is appreciated!