I think these novel ideas are great however as said you would have to price around and take into consideration the price of these umbrellas and weigh that against the potential of what you want to achieve. If it is just to drive people towards your site without giving any other inclination of what your site is then yes, although you also have to think would people be willing to check out a site with no idea of what it is... or would this work in your favor and the intrigue would see them visiting it. Also you have to take into consideration the fact that people usually get those umbrellas when they are drinking alcohol and therefore the likelihood that they will take much notice and/or remember the URL on the umbrellas may be lowered for this reason. Perhaps if you find something that they may use again -meaning that they will take it home with them and therefore the frequency that they will see your URL will be increased along with the chances of them checking our website. Good luck..
