Effective Internal and External Communications is critical to a smooth running convention operation.
To the Membership
As technology progresses, many cons have begun to use blogs, LiveJournal, Facebook, Twitter, and other such social-networking and -communications services both for pre-con and during-con membership communications: Twitter can be especially useful for this, as you can define an at-con twitter address (@Necro09-Announce), and recommend that members device-follow it (joining up if necessary), which allows you to announce major changes to a statistically signification fraction of your attending membership directly and quite quickly - the messages will be delivered by SMS directly to members' cell phones.
In addition to progress reports and newsletters, the staff will probably need more immediate and interactive forms of communication. Email, restricted access websites, and good old telephone communication work well pre-con. Make a phone list to call the person(s) you need to reach, or set up a phone tree to broadcast a message to everyone in the staff.
Bulletin Boards, literally a piece of paper hung on a cork backboard with a thumbtack, might work for passing messages at-con. Erwin "Filthy Pierre" Strauss is famous for bringing the Voodoo Message Board to Worldcons and some regionals for general attendee use, but chances are you'll want a more sophisticated approach for staff. A central messages desk might work. Put it in a secure place, away from member access.
Handheld radios, or cell phones with person to person modes might work well too. Be sure to check coverage, clarity, signal strength and restrictions before you commit to a solution.
Remember, you never want a disaster. More important, you especially never want to explain a disaster by saying, "I couldn't reach ..."
One particular tactic that might be useful for operational communications, whether you have radios or phones, is to have a centralized dispatcher -- usually located in your ops facility -- with the complete list of contact phone numbers sorted both by position and name. This list can include numbers which will generally actually be used by various interface coordinators like security and logistics, at your discretion; if you do so, you should probably set a policy as to when dispatch should call outside the con directly.
If you have someone in this position who has some experience in the job, this can be a *very* effective method of communications, as it relieves everyone in the field of such things as "they were on the phone"; "couldn't get through"; "didn't know who to call", etc, etc, and the dispatcher can answer the top 10 FAQs without having to refer the call.
If possible, this person should have a couple of house phones available, or a multiline phone -- preferably hunting off the same phone number, which is a public direct-inward-dial -- as well as a log book to note down who's called, who and or what they needed, and whether the message has been delivered or not. (If you can computerize this, so much the better.)
If they have SMS and email connectivity at their position, so much the better. It may not seem economical to tie down an entire body for this job, but the benefits generally outweigh the costs.
Websites for committee collaboration
- Yahoo Groups
- Strong member controls
- file storage
- auto meeting reminders
- Google Docs
- Useful for sharing files, collaborative editing
- Text files
- Ta-da List
- Simple sharable check lists
- Create new items on the fly
- Check them off, without deleting them
- The data remains persistent from year to year.
- Multiple people can add to and check off lists simultaneously.
- good public face
- less suited for real work
- Good for the larger community beyond the committee
- Dedicated web servers
- if you have the resources to host your own site, with collaboration features, go for it.
- Content management systems (such as Drupal)
- Ticketing systems (such as RT)
- Conrunner.net (this site)
- Can be used to create content, but the entire public can see and change it.
- wikispaces.com, pbwiki.com, and the like
- Good member controls
- Free, with advertising
- Strong features, but different enough from mediawiki (the core software that drives conrunner.net and wikipedia.com) markups to trip people up.
- Conrunner.net (this site)
About Family Radio Service radios in general: 
FRS radios are a must for con staff. They can often be purchased or rented by the con at discount from professional communications companies, if done in bulk. Within a broad range of circumstances, they are all inter-operable among brands and type. Advise your staff of the virtues of the units for everyday life. A good set of dual radios with a recharging station is a must for the modern family. They can talk to the kids in the neighborhood, or use them for road trips and camping. Also they can bring them to the convention when they volunteer. Practice is essential, so think up excuses to use them in preliminary sessions. Advise your staff what frequency you will be using before they travel, so that they can be "live" the moment they hit the perimeter, without having to wait to talk to you to get a radio on the right circuit.
So called Privacy Codes are a misnomer. They do not keep your conversation private or secret. They prevent you from being interrupted by the conversations of others. Everyone else can hear you just fine if you use the codes. But you can't hear them if they don't use your codes. Codes are not universally supported. If all your staff's radios supports the same codes, the you can use them to filter out the non-members who may snoop and barge in on your frequency.
Most radios will display their frequency and code to anyone who chooses to look carefully. Trying to keep them secret from non-staff is a pointless exercise, but if you must, you could tape over the relevant portion of the display. However most good radios have a scan function and anyone can soon discover your frequency.
Most good FRS radios usually come in dual sets with a combined charging station. However they are vulnerable to wall wart crowding as anticipated in Logistics#Power Requirements