Market researchers and analysts continue to buoy up podcasting's future with latest figures suggesting a US audience alone of 56 million by 2010.
Broadband and portable music player sales have fuelled growth
Podcasts, which are only a year old, are online audio shows by amateurs and professionals which can be sent automatically to digital music players.
The forecasts come just after Apple released its version of iTunes which includes a directory of 3,000 shows.
The predictions also match those for growing digital music player sales.
Apple said that by providing a directory of 3,000 podcast shows, it was taking podcasting into the mainstream.
The early forecast by The Diffusion Group (TDG) is an indication that podcasting has captured the imagination of digital music player owners who demand to listen to more than just music.
Major international content providers, such as the BBC, ABC News, NBC News, Disney and even Nasa have started to make their programmes - usually ones with no music - available as podcasts to download.
The BBC's podcasting trial includes 20 radio programmes, such as the World Service's technology show Go Digital and Radio 4's In Our Time.
But there are still thousands of podcasts which are being done by ordinary people in their homes, such as the Tartanpodcast, which aims to bring independent Scottish music to a wider audience.
TDG said the audience for podcasts last year was around 840,000, but such figures are difficult to accurately measure.
They also tend to focus on the US market, rather than the global one.
It said that by 2010, three-quarters of all people who own portable digital music players will listen to podcasts, a growth from less than 15% last year.
The figures are based on data from portable digital music player sales and high-speed net penetration.
Statistics on podcasting have differed recently, however. Analysts Forrester Research predicted in April that 12.3 million US households would be using digital music players to listen to podcasts by 2010.
Figures from the Pew American Life Internet Project earlier this year suggested that six million Americans were already listening to podcasts.
This figure was criticised after it was revealed that the questions in its survey could have been confusing.
Podcasting is something that started and has continued to grow outside of the conventional big media market.
The audience growth is being fuelled by the rise in popularity of digital music players, and people's desire to take more control of their digital content, listening and watching what they want, when they want it.
Big media companies are keen to get into podcasting
Jupiter Research recently predicted that US digital music player sales would grow to 56 million by 2010, up from 16.2 million in 2004.
The desire to "time and place-shift" content has been demonstrated by the success, for example, of digital video recorders such as TiVo and Sky+ type set top boxes that automatically record your favourite TV programmes.
The increasing availability, take-up and speed of broadband which means downloads are much faster has also meant people have the opportunity to get more from the net.