Online productivity tools are a great way to keep you organized. I think the best approach is to try out one or two (i.e.: calendar & to-do list) to see how time consuming they are to keep up. As I stated in a previous post, these tools are only as useful as the information that you put into them. If the time spent on upkeep outweighs the benefit, then even if these tools are awesome, it wouldn't be worth using them. Just the knowledge that they are out there is beneficial.