If you go down to US frequent enough, buy a T-Mobile Mi-Fi. $10 for 200MB/week (whichever first) or 30 for 1GB/month. I have yet hit the limit in the 10+ occasions that I recharged. And this is with iPad playing youtube/PPTV on the road.
I bought mine off local Craigslist for $50. Then just load it up whenever I go for anything longer than a day. Then use Skype on my iPhone/Android whenever I need to call someone.
The speed is awesome if you are in their *4G* coverage.