I have been using Padlet (formally Wallwisher) in my classroom since discovering it on Heidi Raki's Resources Blog and I love it!
This is literally a "virtual wall" where students can write and collaborate on anything. The teacher can set up the "wall" and assign tasks for the students to do. In my first grade classroom, I have been using it to help with writing basic sentences. I have been assigning a "word of the day" and the children come up with a sentence. The students then create their sentence or whatever you have asked them to do. The children in my class are so excited to write their sentences - they are literally clamoring at the bit to get to our computer to type a sentence. It is also great for our non-English students as it helps them with sentence structure as well. We then take a look at the sentences and correct for spelling, verbs, and punctuation.This also allows me to do a quick assessment on capitalization, punctuation, sentence structure, etc.
Search the internet for other uses of Padlet in your classroom - you will find many creative ideas.