I have only been an expat for a few months, but I'd be happy to throw in my $0.02.
Top five ways the internet impacts my life as an expat -
1) With VOIP, I have a US phone number so my family can ring me here just as if I was still back in US. I can call there as well, all for around US$20 per month.
2) When a phone conversation is not enough, I turn on my webcam for a family chat so that we can see and hear each other.
3) The internet brings US tv (news, sports, and entertainment) to my screen here. New devices even let expats watch their local news from back home (see:
www.slingmedia.com)
4) Blogs keep my family up to date with what I've been doing, and vice versa. This helps us maintain connected with each others lives.
5) Of course, there's the 'old standby,' email. Almost seems low tech by today's standards, but reaching just about anyone across the globe instantly is still an amazing feat.