Clickthroughs/TOSes/Shrinkwrap licenses: How obnoxious can they be?

Prompted in large part by this, as glossed here and here.

I think we all know what I’m talking about here: The licenses that begin "By [viewing this webpage|clicking this button|ripping this cellophane], you hereby agree to [do|not do] … " The contracts that don’t require signatures, notaries, or handshakes, merely an action you are intent upon doing anyway. (That is, the specific action mentioned in the contract is not occasioned by the contract itself, merely by the normal usage of the product or service covered by the contract.) I can be more specific only by citing examples, which I am willing to do.

They seem to get longer and longer, and list more and more absurdly draconian penalties, and I want to know if there’s an upper limit to the limitations they can impose or the penalties they can inflict. For example, can a contract of this form constrain one from placing a phone call to the company issuing the contract on pains of a $150 fine? Can a contract of this form presume to impose limits on my usage of a product that would nullify fair use?

Or is this all up to case law and the mood of any given judge on any given day?