How many ways can a person send a message these days?

Well, how many ways can a person send a message these days?

• Talk to a person.
• Join a group conversation
• Write a letter to a person
• Write a letter to the editor
• Call a person on the phone
• Call into a broadcast show
• Participate in a conference call
• SMS (text) on cell phone
• Email
• IM a person
• Join an IRC or IM chat room
• Update your status on your IM service
• Send a message on a social networking site
• Update your status on your social networking site
• Tweet
• Write a blog post
• Comment on a blog post
• Post a comment on a forum
• Send a message in your virtual world or MMORPG
• Produce a podcast
• Participate in a webcast
• Um, yikes, that's a lot, but it's not hard to come up with more.  Put a message in a bottle.  Update a bug report.  Post a sign.  Spray-paint your house.  Wear a message T-Shirt.  Put a bumper sticker on your car ...

I'm limiting (yes, limiting) myself here to things a typical individual might be expected to do, so writing a magazine article or holding a nationally televised press conference wouldn't count.  Even so, there's a seemingly limitless supply of ways to send a message.

When faced with such abundance, a plausible explanation is combinatorial explosion -- a reasonably small number of factors which can be combined in a large number of ways.  What are some possible factors?

• Cardinality:  How many senders and how many receivers are there? The choices for each are one or more than one (denoted N) This is why I distinguished calling a person from joining a conference call or phoning into a show.
• Symmetry: Are there specific roles, e.g., sender and receiver, or is everyone on an equal footing? 
• Potential recipients:  Who could possibly receive the message, or perhaps better, what group do you need to belong to in order to be able to receive a message?
• Potential senders: For the purposes of this exercise, this is generally "Anyone" (though in some cases it's narrower).
• Access control: Who controls who can send or receive?
• Persistence: Can the message be expected to be permanently available to the recipient?  This would be within the messaging system.  Once a message is received, the recipient can generally keep a private copy and/or resend it.
• Latency: How much time typically passes between sending and receiving?  Latency can be higher or lower.  It can also be arbitrary, as in the case of forums and email.
• Bandwidth: The maximum rate at which information can be transferred
• Message size
• Anonymity: Does the sender typically know who is receiving?  Does the receiver typically know who's sending? If so, can one easily make oneself anonymous?

So does that help sort anything out?  If it does, we should see a fairly wide variety of combinations, keeping in mind that some particular combinations may not make sense.  For example, 1:N cardinality implies asymmetry and persistence generally implies arbitrary latency.  Let's see what we've got (the table below is too wide for this layout, so I made it scrollable. Here's how)

Mechanism	Cardinality	Symmetric?	Potential receivers	Access controller(s)	Persistent?	Bandwidth	Message size	Latency	Anonymity
Talk to a person	1:1	Yes	Anyone	Participants	No	High	Arbitrary	Negligible	None
Group conversation	N:N	Yes	Anyone	Participants	No	High	Arbitrary	Negligible	None
Letter to person	1:1	No	Anyone	Participants	Yes	Low	Small	Days	Possible for sender
Letter to editor	1:N	No	Subscribers	Editor	Yes	Low	Small	Days	Possible for sender
Call person	1:1	Yes, except at start	Anyone	Participants	No	Medium	Arbitrary	Generally negligible, enough to be annoying in some cases	Possible for caller or receiver
Call show	1:N	No	Listeners/viewers	Producers	Typically	Medium	Generally limited	Generally negligible	Possible for caller; audience is anonymous
Conference call	N:N	Depends.  In some cases only some participants can talk.	Depends.  Passcode may be required	Moderator	Depends	Medium	Arbitrary	Generally negligible	Possible
SMS	1:1	No	Service subscribers	Service provider	Yes	Low	Small	Arbitrary	To the extent phone numbers can be anonymous
Email	1:1 or 1:N	No	Anyone with email (doesn't matter who provides the email service)	No one, except that various providers may try to screen out spammers	Yes	Low for typed text, can be high for large attached files	Varies, but generally at least megabytes	Arbitrary	Possible
IM	1:1	Yes, except at start	Service participants	Service provider	Optionally	Low (again excepting file attachments)	Low (again excepting file attachments)	It's "instant" messaging, right?	Possible
Chat room	N:N	Yes, except at start	Service participants	Service provider (for access to service), moderator, in some cases (for access to room)	Optionally	As with IM	As with IM	As with IM	Possible
IM Status update	1:N	No	Service participants	Service provider	May or may not be archived; persists until changed	Low	Small	Arbitrary	None
Social network message	1:1 or 1:N	No	Service participants	Participants, service provider	Yes	Low	Generally small	Arbitrary	None
Social network status update	1:N	No	Service participants	Service provider	As with IM status	Low	Small	Arbitrary	Default state for readers
Tweet	1:N	No	Anyone with a web connection or cell phone	Service provider (Twitter)	Yes	Low	Small	Arbitrary	Possible for sender, default state for readers
Blog post	1:N	No	Anyone with a web connection	Blog author	Yes	Low	Smallish	Arbitrary	Possible for author, default state for readers
Blog comment	1:N	No	Anyone with a web connection	Blog author	Yes	Low	Smallish	Arbitrary	Possible for author of comment
Forum comment	1:N	No	Anyone with a web connection	Moderator	Yes	Low	Smallish	Arbitrary	Possible for author
Virtual world/MMORPG message	1:N	No	Service participants	Service provider	No	Low	Small	Generally negligible	Players go by pseudonyms
Podcast	1:N	No	Anyone with a web connection	Creator	Yes	Medium	Largish	Arbitrary	Possible for creator, default state for audience
Webcast	1:N or N:N	Depends, as with conference call	Anyone with a web connection	Moderator	Possibly	Low	Low	Generally negligible	Possible

One could argue over particular entries, some of the terms could be better defined, and I could add other factors, for example privacy, but it's pretty clear that combinatorial explosion is exactly what's going on.  There are a zillion different ways of sending messages because there are a zillion possible combinations of features one might like.