You may find description of integration plugins and how it works here.

Title/Link Type Different userg roups support "Single-login" support

Dokeos is a open source online learning
suite. It provides Learning Management, , Oogie Rapid Learning, Accurate
reporting and Videoconferencing.
Content Management Systems (CMS) Yes Yes

Drupal is an open source content management
platform. Equipped with a powerful blend of features, Drupal can support
a variety of websites ranging from personal weblogs to large
community-driven websites.
Content Management Systems (CMS) Yes Yes

An affiliate management script
Other.. No No
Invision Power

Invision Power Board, an award-winning scaleable bulletin board system,
allows you to effortlessly build, manage and promote your online
community. Advanced yet intuitive features like multi-moderation allow
you to focus on developing your community, rather than wrestling with
complex settings.
Bulletin Boards Yes Yes

Joomla! is one of the most powerful Open
Source Content Management Systems on the planet. It is used all over the
world for everything from simple websites to complex corporate
applications. Joomla! is easy to install, simple to manage, and
Content Management Systems (CMS) Yes Yes

Kayako SupportSuite offers true integrated
Multi-Channel solution allowing you to manage your emails, online
issues, chats, self service and issues received by phone. This
plugin uses internal Kayako eSupport Integration abilities, so it works
different way than other plugins
Support HelpDesks No No

phpBB is a high powered, fully scalable,
and highly customizable Open Source bulletin board package. phpBB has a
user-friendly interface, simple and straightforward administration
panel, and helpful FAQ. Based on the powerful PHP server language and
your choice of MySQL, MS-SQL, PostgreSQL or Access/ODBC database
servers, phpBB is the ideal free community solution for all web sites.
Bulletin Boards Yes Yes

Simple Machines Forum – SMF in
short – is a free, professional grade software package that allows you
to set up your own online community within minutes.
Bulletin Boards Yes Yes

Vanilla is an open-source,
standards-compliant, multi-lingual, fully extensible discussion forum
for the web. Anyone who has web-space that meets the requirements can
download and use Vanilla for free.
Bulletin Boards Yes Yes
vBulletin (!)

vBulletin is a powerful, scalable and
fully customizable forums package for your web site. It has been written
using the Web's quickest-growing scripting language; PHP, and is
complemented with a highly efficient and ultra fast back-end database
engine built using MySQL. vBulletin is the ideal community solution for
all medium-to-large sites.
Bulletin Boards Yes Yes

WordPress is a state-of-the-art semantic
personal publishing platform with a focus on aesthetics, web standards,
and usability. What a mouthful. WordPress is both free and priceless at
the same time.
Content Management Systems (CMS) Yes Yes