I would use Wordle to make it fun to practice spelling words in my classroom. I have seen it used in classrooms before and kids loved it. I could also use it to describe things, such as an adjective cloud for a famous historical figure
I loved Edmodo, it reminds me a lot of Facebook. I would use it to connect with other teachers, so that I can ask questions and get advice. I have also heard of it being used in classrooms to assign homework, send out reports, give schedules, and post notes.
I would use Zapd to make little videos to introduce topics in an interesting way.