Reference site for Linux/Ubuntu use in businesses?

[Karl Bowden]

Hey Guys and Gals.

As the title suggests, anybody know of some good sites with reference
material for using Linux/Ubuntu in SME's?

Thinking mainly along the lines of best practices for:
- Mail
- Directory Services
- Knowledge base's
- VoIP
- Virtualisation
- Accounting

Especially for mixed environments, and aimed at Australians (ie accounting).

If not, anybody interested in collaborating on this sort of information?

- Karl