A huge advantage in my book is the break-out room feature in most of the best virtual classrooms.
This is when your own content creation comes into play.
The fun activities one can use to supplement courses and have students creating their own educational masterpieces are endless.
My favourite activities would include comic creation, video-making and story-telling via multimedia.
The British Council also provides a lot of online support for IELTS preparation.
Other great resources can be found at busyteacher.org, EFL classroom 2.0, and Teachers Pay Teachers.