Open University (UK) Open Content Initiative
The Open University, being a higher education institution, provides higher ed content. This content is available in units, which are different size chunks, anywhere from a smaller amount of material that could be reviewed in just a few sessions or a workshop to what appears to be enough material for a full semester course. The materials have learning objectives and are rated from Introductory to Advanced in the level of the material they cover, but they do not provide any clear prerequisites that might be required to successfully meet those learning objectives. There are discussion forums dedicated to allowing for exchange of ideas among learners of the content.
Connexions is a repository of modules and courses (collections of modules). From what I understand about Learning Objects, these modules are basically just that. Each of these modules are quite small, and could be used alone or along with the rest of the course, or remixed in some other way.
Carnegie Mellon Open Learning Initiative
The OLI exists of a very small number of full courses, with all the same material as a student taking the course at CMU, but without access to the instructor or exams. By paying, the student can earn credit by working with an instructor and taking exams. Both methods allow the student to track their way through their completion of the course if desired.
UNESCO Open Training Platform
The UNESCO materials, put out by the United Nations, is not so much focused on higher ed like many of the other OER repositories reviewed here. The OER in this case look more like continuing/distance education or adult outreach education. A byline on the site says they are "Advocating open content in non formal education." I suppose that nonformal in this case probably refers somewhat to the fact that this is not formal university material. A lot of it looked like material that could be very helpful in terms of teaching something people can actually use. I was a little worried, however, by a 10-year-old document covering the basics of getting on the Internet; some of the other information may not change as much in 10 years as that particular topic, but that one was extremely out of date.
This is one of the most well-known OER Repositories, but then again I am most familiar with USU OCW which is modeled after the MIT OCW. Again, we're looking at higher ed material here, and quite a comprehensive set of well over 200 courses published in the last 6 months alone and over 1700 courses altogether (compared to just under 100 or so total at USU). They look to be mostly full semester courses, including presentation of material, additional study materials, and exams. One course even had a pop quiz included. So the students reviewing the OCW content when taking the actual class at MIT might get an extra hint about when the pop quiz will come up. :) These are MIT classes, so a reasonable assumption might be that these are high quality materials.
National Repository of Online Courses
NROC OER consist of higher ed as well as high school level courses. They employ a staff of designers and evaluators to ensure the content consists of effective materials that follow accepted Learning Theories. NROC content is available for educational and nonprofit use for free, or for a price to commercial entities. Similar to the OLI described above, a small number of high quality courses are available.
Some of the differences among these repositories are terms of the licensing of content, the balance between quantity and quality of content, and tools for finding and working with the content.
One of the most useful features of any of these sites was in the Open University, where they have forums to discuss the materials with others that are there to learn the same thing. That interaction is key. Add onto that the myLearningSpace where you can track what you've studied, see what other people have been looking at the same materials as you, and be notified when new items are posted, and this one has to be tops.
If I had to kill one (or two), I'd have OLI and NROC take all their materials and post them to Connexions. I mean, I like the Open University's learning community better, but the fact that Connexions allows anyone to post their material is a bonus. Connexions has some tools for collaboration among authors, but I didn't see that on the learner side. Add the forums and myLearningSpace from the Open University to the collaborative development process of Connexions and that is the ultimate community.
The only thing that could possibly make this ultimate community better would be to take the enormous amounts of material from MIT and dump it by the truckload onto the community.
We'd have something to rival Wikipedia (or maybe we'd just be recreating their Wikiversity project).