Last year, I introduced Google Apps for Education to my 2nd - 5th graders. They enjoyed working on the cloud and especially loved making webpages. Also last year I introduced Glogster.edu to our 4th graders (paid for that one). I'm continuing with those two this year, but adding in voki classroom. For just under $30 you can get 200 logins - voki uses an avatar that students create and then allows either voice uploads or typed script (with a choice of voice accents). Students create these on all curriculum topics and share or post online. We're also using a new Edmodo our school system provides to offer another web tool for students to have input for a classroom. The 3rd-5th graders login to the 3rd grade lab or the 4th-5th grade lab. They had two assignments. One is to learn to make a quick post in response to a teacher request and the other is to vote in a poll. This webtool has the look of Facebook, but does not allow students to post to each other, only as a response to a teacher. Then the post is reviewed by the teacher before it is seen.
I use a wiki for my lesson plans and posting student work or links to their work. Here's to a great year using web tools with students!