This is cylindrical snakeplant, sanseveria cylindrica. It is supposed to grow with the individual spikes in a sort of fan arrangement, but ours don't follow this rule so well. It is supposed to be invasive, but I think it is neat-looking.
We have a ton of this stuff, and I have extra for sale or trade. I usually sell the smaller offshoots on ebay.
Propagation: Divide the offsets. I have also heard you can plant cuttings, but I have not yet tried this.
