Just curious what options are available on Linux to replicate file shares?

We do most of our replication via SAN to SAN...but we have a few servers
with data on the server itself that I need to replicate real time.

Anyone have some suggestions on products? The catch is we need not to be
in a cluster, but rather replicating the data to a DR site over a
dedicated network link. This would be single server at live site to
single server at DR site.