K12Planet.com is a website that allows teachers to post student grades online. These grades can be accessed by students and parents to check a student's progress. Teachers can add messages to a message board for the whole school or just for certain classes or individual students. This can be used to display homework online, and allows school administrators to check grades of students and to post other info such as sports schedules and other events.
Administrators can organize class scheduling through MacSchool, WinSchool or Chancery and can provide usernames and passwords to parents and students. The parents and students can then access the grades through their web browser.
K12Planet and other similar websites (such as Thinkwave and MyGradeBook) allow parents continual access to student performance rather than just at the end of the quarter or through a parent-teacher conference.