I have about 75 kids blog (or at least I assign it! ha!). We use blogger and wordpress. Blogger is so easy, but if you have the kids add on gadgets, you should know that not all are school appropriate. They're not pornographic, but certainly push the edge. Do not let them take the gadget to allow youtube feeds into their blog. The folks at youtube filter in disgusting videos at night. Those two things aside, blogger is a great way to go. Edublogs is extremely popular and designed for students.
Blogger, Wordpress, Edublogs - any of those are great!
- Jessica
ps. Sorry for the late reply. I wish ePals would email me when someone writes back. If you don't get a timely response, my email is jbrogley@epals.com
Here are our blogs!
http://mrsbrogley.com/blog/student-blogs