"Packet Garden captures information about how you use the internet and uses this stored information to grow a private world you can later explore.
To do this, Packet Garden takes note of all the servers you visit, their geographical location and the kinds of data you access. Uploads make hills and downloads valleys, their location determined by numbers taken from internet address itself. The size of each hill or valley is based on how much data is sent or received. Plants are also grown for each protocol detected by the software; if you visit a website, an 'HTTP plant' is grown. If you share some files via eMule, a 'Peer to Peer plant' is grown, and so on."
(from their website)
Looks like Flora meets Darwinia :), and it´s available for Mac, PC and Linux.