The latest idea for sinking our excess CO2 is adding lime to the oceans (the mineral, not the fruit). The idea here is that increasing the alkalinity of the oceans would not only increase CO2 capture but also mitigate the problem of acidification. You'ld also try to get the lime from somewhere that the CO2 involved in creating and transporting it would be less than what you capture.
What's most interesting about this "fix of the week" is that Cquestrate is trying to run this as an Open Source project. You too can help figure out where and how to drop the lime. The Slashdotters have already claimed most of the good jokes, so time for you engineers to dive and be part of the solution. It'll be just like Firefox.