If you're spending more than a couple months in one place, then getting a prepaid mobile
phone is a good idea as it will make your life a lot easier. Just think, if you can't live
without your cell phone at home, what makes you think you can live without it abroad? If you're going to
be looking for work, a mobile phone is essential-- plus its a great way to keep in touch with people at home and those you
meet along the way.
Most countries are on the GSM (or triband) network so as long as your phone is unlocked, you should be able to use it wherever you go.
There are different service providers in each country you go to, so just ask around for the
best deal.
One note- the US is just now switching to the GSM network and thus is prone to problems. Prepaid service
is also somewhat of a novelty.
Here are some links to help you get a mobile phone:
Mobile Service Providers: Amp'd Mobile - Get 3 months ANYTIME minutes
T-Mobile - Get all the time you need! 1000 nationwide Whenever Minutes for only $39.99!
Mobile Phones: Lets Talk - Find and compare cellular service plans
Cell Phone Shop - Cell phone accessories 80% off
Phone Cards: CallingCards.com - Find the lowest pre-paid calling cards
ZapTel - Call anywhere in the US for 1.9 cents / min!