This idea is so obvious I can't believe we haven't done it before. Many people here have posts they would like to write but keep procrastinating on. Many people also have other work to do but keep procrastinating on Less Wrong. Making akrasia cost you money is often a good way to motivate yourself. But that can be enough of a hassle to deter the lazy, the ADD addled and the executive dysfunctional. So here is a low transaction cost alternative that takes advantage of the addictive properties of Less Wrong karma. Post a comment here with a task and a deadline- pick tasks that can be confirmed by posters; so either Less Wrong posts or projects that can be linked to or photographed. When the deadline comes edit your comment to include a link to the completed task. If you complete the task, expect upvotes. If you fail to complete the task by the deadline, expect your comment to be downvoted into oblivion. If you see completed tasks, vote those comments up. If you see past deadlines vote those comments down. At least one person should reply to the comment, noting the deadline has passed-- this way it will come up in the recent comments and more eyes will see it.
Edit: DanArmak makes a great suggestion.