Chamilo is an e-learning and collaboration platform which comes bundled as open-source software (or as puristswill note, ratherFree Software) which can be adapted to educational or professional projects. It is distributed under the GNU/GPLv3+ license, which you are bound to accept when using it.
A teacher using Chamilo can access a series of useful tools allowing them to easily and efficiently create an effective learning environment. On creating/editing a course he (or she) can:
import or create documents (audio, video, images) and publish them,
build tests and exams with automated scores and feedback as required,
set and receive virtual assignments,
describe the components of the course through description sections,
communicate through forums or chat,
create work groups or laboratory groups,
set up a virtual classroom (through the videoconference extension),
manage scores through the assessments tool,
add a wiki to create documents collaboratively,
use a glossary,
use an agenda,
manage a project (through the blog tool),
enable tracking of learners in your courses,
elaborate a class diary (course progress).
The Chamilo platform is extremely flexible. All its tools can be customized according to the needs of each course. It provides a friendly and intuitive user interface which requires no special prior technical knowledge or skills.