3G mobile killer app: Conversational TiVo. Taking advantage of the always-on and high-bandwidth nature of the 3G network, the cellphone keeps a rolling recording of the last 24 hours of audio. At any moment you can jump back in and listen to that name you were told ten minutes ago; archive a speech and email it as an mp3; do voice-to-text on that taxi phone number somebody mentioned earlier this evening; find out exactly what you were talking about in the pub at 10.30 last night.