A good source of repurposing material can come from being aware of what others are blogging about. This could be through the blogs you are associated with, including your own, or from industry related forums that you stumble across. By addressing what other people are talking about and how audiences respond to various comments and threads, you can establish yourself as a bit of an authority on the subject.
If you are yet to jump on the blogging bandwagon, primarily because of a lack of ideas on what to blog about, consider the questions current customers or associates ask you, and if there is a familiar theme, make that the topic of an educational post on your website. If you can fix a problem for someone, you will have made a cyber-friend. Build on that relationship by repurposing that blog into various file formats, such as audio and video, and post on your site, on related blog sites and on the social and video networking websites.
Use your imagination and creativity to find new topics for content and repurpose in order to use and reuse for promotion and profit, well into the future.