If you use an ISP with global roaming access then you'll be able to access the Internet for the cost of a local call in a lot of countries. If you're detached for any length of time it's often easier to open an account with a local ISP. Ideally you should consider getting your own domain name then your email address will always be the same no matter which ISP you're using.
A lot of ISPs let you check your mail via a web based site when you're travelling, avoid Hotmail as it's barred from most US military welfare computers.
Check out
www.gric.com/network/isp_locator.html