Yes, I do, because my mind is too curious to be satisfied with what I can experience in the average life. I want to know what everything is like, see what the future holds, experience things outside of this world, etc etc. So, if I find a method, I'll gladly take the chance to live forever. Sadly, the only possible way so far is cryonics.
EDIT: But I'd only do it if [insert whoever I end up in a relationship with] is also able to do so.