Swap over NFS

Swapping over NFS requires a patch (http://www.instmath.rwth-aachen.de/~heine/nfs-swap/), but is not stable (yet). It is also very slow and insecure (memory pages go unencrypted over the network).

Swap over Network Block Device

Swapping over NBD (network block device) seems to be buggy too; BasVanSisseren reported that swap over NBD crashes after some time (it looked like the client swapped out itself).

Swap over Enhanced Network Block Device

Untested, but you can try. Download at http://www.it.uc3m.es/~ptb/nbd/ .