Help me identify this tree/shrub?

i have a small blog posted at this address with all the info on this plant i cant identify... please post on it and let me know if u can help. thanks. jake
http://uknownplant.blogspot.com/

an upright or tree-form agave.

OR

a member of the bromeliad family.

OR

a tree or upright form Yucca (http://image04.webshots.com/4/4/75/9...0fbfCJi_ph.jpg)