[human_v2]

This is what I would do, but you'd need some prerequisite software and information:

1. Get a genome for the simplest bacteria you can find. 2. You'd need molecular simulation software, specifically DNA and cells

After you've gotten this, I would strip out pieces of the genome using the genetic algorithm (oh the irony) and see if you can slim the genome down to a bare-bones replicating cellular machine.

After that, just a little trial and error and you could be making designer organisms.

(Sorry if you wanted something realistic. My brain doesn't work like that =)

[Maro]

".. slim the genome down to a bare-bones replicating cellular machine .."

That sounds interesting from a computational perspective. Any good papers to read? "Designer organisms" also sounds interesting...