After spending several months and several hours each day creating his lessons piece-meal, I found a couple of wonderful resources. The first is AOL at school: http://www.aolatschool.com. There is an amazing amount of information, links to complete online textbooks and more. This is where I go when he finds a topic of interest and he wants to know more. (Remember when we had to get our parents to take us to the library?) One of the benefits here is that it is FREE! The textbooks range from kindergarten all the way through high school and cover most topics.
The second resource I found serves as the foundation for our homeschooling curriculum: http://www.time4learning.com. Time4Learning provides a multimedia, interactive experience for kids covering all basic subject areas. For children with ADD/ADHD, you can break it down into snippets of 10 minute lessons. Additionally, many of the lessons combine subjects. That is, the "Language Arts" lessons are often on topics of health, science and history. This helps ease my mind considerably, because I can know he is learning educational material when he reads. (Many of the so called reading books from his public school were no more than See Spot Run). The other advantage with Time4Learning is that they set your child up at his/her grade level.
As I said, despite the ADHD, my son is gifted. He is set up to do 2nd grade work (he is in first grade), but he can progress as fast as he can and still master the material, or he can have easy/review days and do grade-level work. For parents, you can create an assignment book that links Time4Learning assignments to the skills they were supposed to learn. I use this to record his grades for the school board to review each year. I have found customer service to be very receptive to suggestions, they are regularly adding new features and their customer support is prompt and courteous.
A third resource is http://www.education-world.com/. This site has TONS of ideas, printable worksheets and activities. Since kids with ADD/ADHD have difficulty switching tasks, it is often preferable to have one "subject" per day and present it in a variety of formats (reading about it, watching a movie about it, applying it).
Other resources include:
Discovery School: http://school.discovery.com/
ABC Teach: http://www.abcteach.com/
FunBrain: http://www.funbrain.com/
SuperKids: http://www.superkids.com/
Everything4Kids: http://www.kapili.com/topiclist.html (This is geared to the older or advanced student)
KidsKnowIt: http://www.kidsknowit.com/
These last resources do not have a syllabus or curriculum, but they are FUN. For the child with ADD/ADHD this is especially important. Some days they are too stressed, tired or focused on something else to concentrate on "the basics." As long as this does not happen too often, it is fine to let your child do an off-topic educational activity that he or she is interested in. In our house it is usually wildlife (http://www.enature.com), dinosaurs(KidsKnowIt) or space (NASA).
One suggestion is to set kid's profiles up with icons on their desktops to only the 5-10 sites they are supposed to go to. My children will often stay on the coputer for hours if they can. Children with ADD get overwhelmed if they have too many choices and things to look at. This helps limit their distractions.
Sean went from a child who would look at a page in a book and say "Far too many words" to a child who reads to me and asks "Was I reading fluently Mommy?" I have gotten the time back in my day to start working part-time again. Between these all of these resources most any child and/or homeschool family can find what they are looking for.