Trying to keep in touch with the folks back home while abroad can be difficult, if not downright expensive. However, with a little bit of knowledge (and the right kind of mobile phone), you can keep your friends and family abreast of your journeys without going broke.
For Americans traveling to Europe, you may be able to use your mobile while on vacation. However, instead of activating your worldwide service through your US phone company (where it may cost you $1 per minute), look into unlocking or purchasing an unlocked phone off of Ebay or our personal favorite, MyWorldPhone.
You will still need a SIM card for your visiting country, so when you arrive at your destination, pop into a local cell phone provider and get one. Many countries don't have monthly plans, and it is quite typical to go in and purchase a new SIM. You may even want to wait to get your phone while abroad, since they almost certainly have the latest models. You can even bring it home and use it with a SIM-based service like T-Mobile or AT&T. Just make sure it's a tri- or quad-band phone, dual-band won't cut it back in the good ol' US of A.
In our experience, we called the US from Italy and it would cost us around $.50 per minute. We quickly learned that using a calling card didn't use any minutes from our phone, and was the equivalent of using the calling card to call home from a pay phone. However, what we found most useful was the ability to make local calls without great expense, as well as sending text messages home.
Thanks mtoz for the photo!