Adarsh Thampy's thought-provoking blog, linked to below, suggests that marketers should move away from traditional buyer personas, and instead focus on content persona, as a cheaper and more actionable alternative.
Having a content persona is about looking at the content that you are creating and observing the patterns: which type of content converts your audience?
Every marketer should have easily available data when it comes to content. I said should because I know a few top firms still don't even have (free!) Google analytics installed. This means that a content persona tactic is very achievable.
Should you throw away buyer personas? Definitely not, getting to know your prospects is still a must, but a content persona ensures that the information you collect for your personas is far more relevant and based on real behaviour.