While doing planning sessions using Rapid Board what are some reasonable ways to make sure each person on the team has a decent enough amount of work for the length of the sprint?
e.g. if you have 10 people on the team, how can you quickly see if 1 person only has 2 hours worth of work? Are you supposed to wait for them to speak up or can this be done through Greenhopper somehow?
The best way to make sure that everybody has work to do throughout the sprint, is to let them sign up for work every time they complete the previous task. This means that the members will be "pulling" work, rather than having their work "pushed" onto them.
If you conduct a daily scrum - daily - you will find out pretty quickly that someone is not signing up for new work - that he's either stuck on what he has, or not picking new work. Essentially, if you break up your work into small enough tasks, you will know what is going on within a day.
All this will work for you regardless of which software tool you use to track your sprint.