We have new neighbors in our apartment building. They have kids older, younger, and similar ages as our kids. As has already been mentioned, barriers break down quickly in the foreign service - if you only have 2 years to be friends with someone (or less!) you waste less time finding out if you want to be friends.
The wife suggested a babysitting exchange: after the kids go to bed one evening, we go out while one of them comes down and stays with the kids. Another night one of us travels the stairway to do the same. We had our first test this weekend, when Terry and I went out for a belated birthday dinner (I inconveniently had the flu over his birthday weekend, even on the big day itself. I guess it's lucky that he doesn't think it's any big deal. He went to the hockey game that night anyway). We were worried because the night before Zoltan had been up about a million times before our bedtime, so I was ready for that "he won't stop screaming" phone call. Nope, the kids didn't make a peep all night.
This weekend will be our turn to monitor a sleeping house. Keep fingers crossed for us that it works out as well as the first run.
I know in the USA - where babysitters are exorbitantly expensive, at least compared to here - friends may not live bathrobe-and-slippers-commute close, but I do think it is a brilliant way for couples to get a bit of alone time outside the house. At first, Terry said he didn't want to do it too often because we can't necessarily afford to go out all the time. My perspective is different: if we do this regularly, there's no pressure to "do something special because we're paying a nanny for this". We can just take a walk, check out an art gallery, get shwarma and sit in the park.