What should the penalty for threatening to rape someone be?

I can't speak to the U.K., but generally in the U.S. a threat become the crime of assault only when it accompanies an action which shows the verbal threat to be serious.

"Can Verbal Threats Be Assault?"

It depends on the specific laws of a state, but generally no. If the one person only uses threatening words, but does nothing more, it will likely not be considered assault. However, there are situations where threatening words coupled with other acts and circumstance may amount to an assault."

http://criminal.findlaw.com/criminal-charges/assau...

This of course makes sense. Not all "threats" are the same. Most of use have had someone say they want to kill us, but we know that it's largely an empty threat. Tearing off someone's clothing, putting a gun to their head and saying you are going to kill or rape them if they don't do what you say is a threat of a whole different nature.

Moderate assaults are often a misdemeanor, more serious ones can be prosecuted as a felony.

It should be whatever the law says, for uttering threats. That is already illegal, in most civilized countries. I imagine it is not legal, even in "uncivilized" countries. Too bad so many people don't take it seriously, when angry morons threaten women with rape, in some desperate attempt to silence us.

They should be Banned from the Internet for a Month. Maybe THAT would teach Them to keep Their Threats to Themselves. ;)

30 days in jail