LearningSpace has an klear and well structured interface, but it takes a little while to look around. It offers a great deal of different fields and provides flashmeetings and videobloggs among other things.
Connexions seems to provide a meeting space for specifically the educational field. The interface is clear and easy to navigate In. it also had a good virtual tour of the website.
A bit different from the first two, this site provides online courses in a wide range of fields. The only problem was that most of the courses notes were dated a some years back and I didn’t find many newer courses. It seems like the interest in contributing isn’t that big. I was also quite bothered about the big “donate now” signs…
The best thing about LeMill is that you can choose form a good selection of languages you seldom find as an option. It feels like it is a community for Europe. The freedom of choosing ones own language is good, but it also makes the learning environment a bit difficult to use because of the postings and discussions in languages one doesn’t master. LeMill doesn’t yet have a very large database (or so it seems)
Wikiversity is quite clearly structured and easy to use – interface familiar through the use of Wikipedia. Wikiversity seems to hold a lot of material, also in the field of education and has nice demos.