I realize "swaps" aren't much en vogue chez les Allemands? All the sites I found are located in the US, not a single one in Europe.
The sole swaps I found for Germany were rather clubs of sorts, who'd exchange stamps and music samplers. Not quite the same, I'd say.
Some of the US swap groups are open to international members, some aren't (I think it is because they exchange parcels rather than padded envelopes, so postal rates could become a problem. Or a burden. Pick your guess...).
Not always easy being the early bird.
I am going to find me a nice group in the US.