Has anyone got any effective methods for taking snapshots of data.

I have one table, that has one-to-many relationships with quite a few tables. At certain points in the system, a snapshot of this table needs to happen, and the other tables will need to reference the [historical] data at the point in time the snapshot was taken.

Hope that makes sense, we have many ideas to tackle this, but they all seem nasty, so I'm looking for a nicer way to do it.

Any ideas?

Thanks
Kev