Listserves, or discussion groups were a huge hit in Web 1.0, and are perhaps the granddaddy of all online collaboration. They are still widely used, and perhaps you could also say widely abused.

Advantages of Listserves

• freedom of speech - you can say anything you want, using as many words as you like. This is good for teaching, and good for sharing of personal views and feelings.
• easy to use - once people are signed up, the interface is easy - nothing else to learn if you know how to email.
• current - information presented to you on a listserve is new by its inherent design.

Disadvantages

• freedom of speech which also includes ranting, flaming, misunderstandings and people who don't know when to stop. Listserves are particurly bad for negative feedback loops as those who feel slighted always want to have the last word. See email rage.
• Tuning out - often inidividuals will automatically filter or file away emails sent to a group, so that they are only being read when that person makes an effort to check the list. Web-based lists also offer web only versions for the same reason. In a listserve you can never be sure the person you are talking to are paying any attention.
• the memory leak - listserves tend not to conserve or preserve knowledge, and does not consolidate discussion into wisdom - all that talk/information is generally delivered once and then deleted or lost in backupland.

Best Practices:

• Use listserves for the same reasons that you use email, except in a group situation.
• Do not use listserves for actually deciding or managing anything
• do not try to have meetings by listserve.
• can be used for meta discussion about what is happening in a wiki or intranet
• may be considered a "backup" means of communication if people have trouble with the technology or finding stuff.
• need to have a minimum number of people who are actively monitoring the listserve.
• all listserves should have a code of conduct or some other participation policy which is boldly enforced. Allowing even minor rudeness can lead to escalating tempers and negative impacts on team output and morale.