Ask HN: Mobile Broadband sateside

Hopefully you can figure out a bit of a conundrum for me :) Im coming to the mighty US for a holiday later this month. As it's 3 a week trip roaming new england etc. Im taking my Netbook so I can keep up with emails and book hotels etc. Problem is that my mobile broadband costs a fortune there: it's a blooming monopoly. ALL UK providers are charging about £6 per MB. Fair enough I expected some premium.. but in the UK they charge that for about a GB! So. What are my options. Mostly I want to rely on free/cheap wifi - the mobile is just contingency. How much cheap wifi is there kicking around over there? NY I assume wont be a problem but we are going round New England and inland a bit (Boston, Niagra, Chicago, Washington possibly). Secondly what are the chances of me popping into a phone shop in NY when I land and picking up a cheap pasy as you go dongle? A traveller to the UK probably couldn't do it because they do credit checks and want you to be a resident etc. Any ideas gratefully appreciated - staying online for the 3 weeks will make things soooo much easier :) EDIT: I know this is a bit off topic for HN - but your about the biggest US community I hang out at :)