In the web design community, the use of moderated forums has been huge for the advancement of best practices and crowd-sourced customer support. Two examples that come to mind are:
Communities like these help to quickly answer user's questions, offer helpful advice, share experiences, etc. This would add a human voice to the often dry and frankly, unreadable instructions found on most .gov websites.
Forums should have official moderators to ensure accuracy and keep things organized and on-topic. But general users should make up the bulk of content produced on these forums. Moderators and visitors should be clearly differentiated visually (see "Moderator" posts on wordpress.org/support).