There don't appear to be many
HR related jobs on the Seek volunteer site at the moment, just a couple of recruitment roles. I'm guessing they don't get many because
HR isn't listed position type. There are quite a few Board positions but they will almost certainly be on-going, longer term positions.
Kim, assuming this is what you want (
HR related work), I would suggest contacting organisations directly at a senior management level to ask if they could use an experienced
HR practitioner on a voluntary basis. Obviously you will need to give them some idea of your availability.
Before doing so you might want to think about what sort of organisation you want to work for, because they may differ enormously. Be aware that not all "Not for Profit" organisations are necessarily charitable organisations.
Kevin