Top Education Degrees recently published a list of 10 useful online applications for teachers. Here's a blurb:

"Teachers for all levels of students today have so many more teaching aids than even just a few years ago. That's not just because of greater access to the Internet but also because of the growing number of web applications that they can use. Some applications are specifically geared towards teaching and learning. Other applications can be adapted for these purposes. Here's a list of some online applications, listed alphabetically, that we feel are excellent for teachers."

Among the links are a multimedia content builder, an educational blogging system, and a virtual grade book. Online teachers, in particular, can benefit from many of these resources.