COVCELL means Cohort-Oriented Virtual Campus for Effective Language Learning and its development was funded by the European Commission. It is a collection of activities, with applications such as Audio Recording, Whiteboard, Chat, and a few others. The important ones for testing speaking are the Audio recorder and the Audio-Video Conference. This is similar to the Skype video conference, in that you are able to invite members of your course to a video conference. This is a very useful tool for testing speaking skills such as conversational strategies or fluency.
The big drawback to the COVCELL is that it has not been updated for a while and it is fussy about system requirements. You will need to have your system administrator install a specific server, Red5, in order to use COVCELL. If you are on a hosted server, chances are that you will not be able to use it, and since many people are using hosted servers or are not able to change the system they are using, this isn't practical...