Log on. No password required?

In many cases, "go to Web site X" is more accurate than "log on to Web site X." If you're entering a username and a password, fine. But beyond that, there's just no "logging in" going on.

And then we have the question of using one word or two.

"Login," "logon," "logout," and "logoff" function as adjectives:
This is our logout page.
Update your login information.

"Log in," "log on," "log out," and "log off" function as verbs ("verb phrases" if you want to get technical):
Log in here.
You should log off before you leave work.

You also want the two-word forms for verbals (a verbal is a noun or an adjective that was derived from a verb):
Logging in is easy. (Here, "logging in" is a noun. It's the thing that is [verb] easy [adjective].)

The emperor's new asterisk

So you're reading along and you come across something like this:
When Joe Schmo thought the microphone was off, he said, "Proposition 90 is s**t."

My hunch is your brain reads "s**t" and readily understands it as "shit." Am I wrong? I don't think I'm wrong.

So let's figure that we all easily understand "s**t" as "shit." Effectively we have an alternate spelling of "shit."

If you really wanted to make the profanity obscure, you'd use something more along the lines of:
When Joe Schmo thought the microphone was off, he said, "Proposition 90 is [obscenity]."

Unless you're legitimately concerned that your publication will be read by children, it seems silly to protect adults from the offensive character set "shit" when you print "s--t" with the understanding that they'll fully comprehend it as an alternate spelling.

But the funny thing is, I sense that adult readers are happier reading "s**t" and comprehending "shit" than being confronted with the horror of those extra two letters.