the CHOC Board
a Christian Home School Resource Directory for the extended Portland Oregon metro area
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Curriculum Publishers: New
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Early Childhood & Primary Grades
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Online Classes
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Unit Studies
Online Classes

not just course material but actual classes taught by a teacher online
Alpha Omega Academy offers online courses in a wide range of subjects and grade levels based on their Switched-on-Schoolhouse curriculum.  Choose between their full diploma service program with teacher grading and support or independent study. Single course, part-time or full time offered.
GCF Learn   Goodwill Community Foundation provides a site to learn for free consumer math, life, and computer skills.  We've looked through the computer skills (Word, Excel, etc.) and found them thorough. (We've not looked through their life classes and suspicion they are secular adult in worldview and likely not appropriate for most homeschool children.)  There are different options for the courses--you can either go through the self tutorial (which provides tests) or sign up for one of their online seminars taught by an instructor in the field who provides a CEU completion certificate.
Homeschool Science Academy provides online science classes from a Christian creationist/young-earth worldview.  Taught by a veteran homeschool father who is a college university professor and director of a university science lab.  Classes are geared towards students interested in careers in medicine, physical therapy, boiology, dentistry, forensic science, nutrition, etc.

 Khan Academy is a non-profit organization that provides free online video lessons including math from basic arithmetic through calculus as well as history, science, SAT prep, economics, computer science and more. Amount of video coverage varies between topics, so this is likely a good supplement rather than a full course, however some homeschoolers have used the math videos with great success for high school upper math and SAT prep. Reported as secular but well done and fairly balanced. 
 LIVE Online Math provides online math courses.  Purchase full interactive teacher graded classes to independent study parent graded courses.  Pre-Algebra through Algebra II currently offered.
 Lukeion Project is the efforts of Regan and Amy Barr, archaeologists, university teachers, and Christian homeschooling parents.  They bring classical Greece and Rome alive to their online students through real time classes with vibrant illustrations. Subjects include Greek and Roman History, Latin, Mythology, Art & Architecture, and Greek & Latin Word Roots.  Sign up for a semester class (high school college prep level) or for a 4-week workshop (ages 10 and above).  Discounts available for additional siblings or for audits.
 Northstar Online Academy offers a full service online academy or individual courses that can be parent-directed.  Both academy courses and indepent-learning courses are completed through their online material. Student community available. Wide range of subjects prepared from a Christian perspective for grades 6-12.
 PA Homeschoolers AP Online Test Preparation offers online AP test preparation courses in a wide range of subjects for homeschooled students across the county.  Recommended by Mary Pride. Advanced Placement (AP) tests are given in May of each year. (AP tests offer advance placement for college admission and sometimes college credit as well.)
Potters School  seeks to utilize the benefits of modern technology to aid homeschooling parents.  It offers a variety of junior high and senior high classes which can be purchased individually to supplement a family's homeschool.  Subjects offered include upper math, writing composition, foreign language, sciences and social studies.  All courses are from a biblical Christian worldview and are offered entirely online, supported online, and require participation in a weekly 90 minute live video classroom with a teacher.  Teachers evaluate the student's course work and provide grades which the parent can then insert into the family's homeschool transcript. 
Talisker's online tutorials are live audio and chat sessions that meet for almost two hours once a week, running from late August through early May, in which the students and tutor discuss the material being studied, go over the students' work, and preview the work for the next week. Science, Math, and Literature offered for upper-junior high through high school level.
Ten Talents Tutorial Online Social Studies courses from a Biblical perspective.  Government, Economics, Business, and U. S. History for high school students.
Thinkwell Homeschool online packages provide a 12-month subscription to their online video instruction, 50 hours extended support, interactive exercises, pre-tests, tests, and notes...for a very reasonable price (currently $125 per subject for the basic package described above).  Subjects include 6th grade through 12th grade math (through calculus), and AP biology, chemisty, physics and American government.  An optional workbook and video cd may be bought to supplement the online course (but are not sold separately). These are secular videos, so the subjects are taught from a secular view point, and the math is taught by a college professor who used to be a stand up comic and who has a bit of fun with the dry topics occasionally. However the math appears to be basic math concepts and humor overall clean.  Subscription is not refundable so view the sample demos carefully first.  The math packages are reviewed and recommended by Sonlight for homeschoolers (and sold through Sonlight as well).

This particular article lists numerous places to find more online class resources, many taught by reputable colleges (non-credit but free).