Planboard is a new site I just learned about that is an online lesson planning tool for educators. You can import curriculum standards and multimedia content into the lesson plans, making it easy to organize everything. You can share your plans with others and print out PDF copies if needed. It's also very easy to rearrange plans due to missed classes or schedule issues. You can take notes and reminders in Planboard so that they are organized with your lesson and you can reuse your plans from year to year. It is also very easy to edit a lesson plan so it's easy to make updates or changes as you think of them.
You can also create custom period names and rotating schedules for weekly or daily rotations.
It's not free, however. You can register for a free 30 day trial period to see if you like it. After the trial period ends you can either upgrade to a paid account or just leave. A paid account is $29.95 per year with no limits. There is volume licensing available also.
Disclosure: I did NOT receive any compensation or benefit from this article.
Evernote for Education - what I use to organize and plan my lessons
LearnBoost - free online grade book and lesson planner and more
Using Technology to Organize Your Lessons and Resources