Janet, thanks for sharing this site. I've just added it to my Web 2.0 training. One of the things I struggled with when I was in the classroom was having the links available in one place for the kids to access. I did it by "shooting" the links to the desktops of the computers, but the kids could delete those. This site certainly solves a lot of those problems.
That is one of the cool things about this site... unless someone stops recieving updates from a webmix, they cannot change it. I am now using it for my trainings. I create a webmix for a specific training, share it with the participants and if I see that I want to add more to it, they get the updates too! My teachers love it!
I just have to remember to click "update webmix" after I add something.
Another thing I do is place a link to a Google doc that I want to use for collaboration during a workshop. I'm conducting an Essentials class right now and I have a webmix just for that class that includes links to the wiki, blog, and documents I am using during the training. The participants really like having all of that in one place and all they have to do is click on it.