Modern communication methods, specifically the internet and mobile phones - because I remember exactly what it was like without them.
Back in 1994-95, I spent a year in north-eastern Germany as part of my university course. I was in a very small town in the middle of a very poor rural area which had been part of the GDR, so the culture was completely different, and barely anyone spoke English.
It improved my German no end, but it was also a very very lonely experience, because it was so hard to contact people back at home. I had to use a phone belonging to the school or public pay-phones to contact my parents and DH (then DF), and because of the cost, we only spoke weekly at agreed times and then could only make short calls. We sent letters as well, of course, but still.
I've just been teaching some undergraduate students who came back from their year abroad this academic year, and I know that they will all have been able to keep in contact - sometimes instant contact - with all their friends and family whenever they want to, and they will have had a much easier time as a result.