table replication, without master-slave setup

Hello,

I have a certain setup, so that two computers are running nearly
identical databases: identical setup, tables, users and permissions,
only the contents differ. Now I'd like to keep them in sync, WITHOUT an
extra machine, hence master-slave setup. The problem is, that either one
could fail eventually. Either one or the other machine (with the same
database) get data, but not yet both at the same time. This is some sort
of load balancing.
Is there software out there that "rsyncs" database tables both ways? Or
will I have to write scripts for this task? I've already taken a look at
Slony but it is unfortunately a "master to multiple slaves". And I want
both (or maybe in future three) machines to communicate with each other.
That means one gets data, and sends it to other machines running the
same db.

Cheers,
Alex

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