I didn't believe podcasts could add much value but having read about how easy they are to set up and how the content can be created (e.g. an interview between yourself and a client or a partner company); I realised that actually having some regular content recorded is more likely to get subscribed and listened too.

An interview could then get transcribed and made available via both email newsletter and as a podcast - killing two birds with one stone. Include some visuals on top of it and add it to YouTube as per my previous post!

I hope this gives you some ideas...