Click-wrap agreements and consent 

 nic.suzor has a couple of interesting posts exploring the different ramifications for enforceability of shrink-wrap and click-wrap agreements:

if clicking on "I Agree" is characterised as signing the contract, it looks like you will be stuck with all the terms but, if it is "just" conduct leading to an inference of acceptance, then the ticket cases may apply and the "vendor" may have to show that it has taken reasonable steps to bring specific "surprising" clauses to your attention ...

 have a look here and here.

Then, have a look at s 10 of the Electronic Transactions Act 1999 (Cth) which has various state counterparts.