I found this tedtalks.com presentation by David McCandless really enjoyable and enlightening. I particularly liked the way he had mined data from unstructured sources and then brought it to life visually. There were also some wonderful choices David had made to make his visualisations more usable:

• containment – David showed OPEC’s climate change fund contained inside it’s revenue
• categorisation – David showed types of spend in the Billion Dollar-o-gram to show type and also in the fears chart
• making figures relative – David re-cast figures of spend on military budget against GDP and allowed a clearer comparison
• comparison – David gave charts something to compare against e.g. UK budget deficit where the user might have needed something that made more sense to them against which to compare.

Do take the time to watch it. You’ll feel inspired!