When talking futurism, it’s hard to get much better than Robin Hanson, if you want to remain grounded in the (current) tools of economics. A video of a recent talk he gave is up for viewing on the internet, and it is well worth a watch. It combines a lot of complexity theory, with fairly straightforward exponential growth models to paint a pretty awesome portrait of the future (1000% economic growth doubling every 2-3 weeks? POSSIBLY!).
Or, if you follow Robin’s blog, pretty much standard fare ;].