I use Kidblog regularly with 4th and 5th Graders. Actually I'm the tech teacher and I've gotten my kids set up, then the classroom teachers use it. They love it. It is incredibly easy to set up, group students, and user friendly. I'll send you the new links to the blogs so you can see what they've done with them.
I use two tools from the web on a regular basis (btw I teach seventh grade). One is classtools.net. There are many web 2.0 tools on their but the one that I use most often is the random name picker. When I am choosing students (most often to participate in a warm-up), using the random name picker is great. I copy and paste my class list into it, press fruit machine and a slot machine image comes up with the names. It spins through them finally stopping on one accompanied by cheers. It is great! Or you could click on typewriter and a name will also come up.
You need not only use it for names. This can be used for vocab words or short questions. There are many funb and useful tools for teachers on this site.
And for any timing that you need to do in class, I suggest the online bomb timer at http://www.online-stopwatch.com/bomb-countdown/full-screen/ . Open it set it for five seconds and hit start to see it.
These are great on the Smartboard.
I just discovered Schoology, a social networking platform that is safe, easy to use and FREE. It is a learning management system similar to MOODLE and Blackboard combined with a social network like Facebook. Awesome! https://www.schoology.com/k12.php
So far, we are very pleased. They created a specific domain for our district and have been very helpful with any support issues that have occurred. (All free of charge.) Several of our high schools are using it extensively. The calendar feature which allows assignments from all classes to appear in one place is a big plus. Our elementary schools (K-3) are primarily using it as a teacher tool but I think it is useful with fourth grade and up for an introduction to appropriate online behavior and as a safe "Facebook-type" experience.
Edmodo is wonderful- the kids can access their material at home, you can send links/files to them- you can control the chat - but they can never write privately to another student. We are using it in grades 4-12 (more on the 4-8 levels).
If you decide to use it, I would get your own free domain. This provides some usage information and will give you some admin. rights. This is also free.
Edmodo is always improving their product- the new quizzes are good.