ePals is another Web2.0 tool that allows you to connect your classroom with others across the nation or across the globe. You can search for other classrooms by students' age, content, language, etc.
ePals provides you with student email accounts, blogs, etc. that are free and easy to use. The tool also provides free translation in eight languages. The free email, SchoolMail, can be monitored by teachers, administrators, IT staff, etc. and can be set up to automatically block teasing, hate speech, sexual harassment, cursing, etc. It includes virus scanning, spam protection, and even a Spell-checker. The SchoolBlog allows you to set up classroom only portions, parent only portions, and public sections of your blog.
Suggested by Daniel Przbylski