What is that turtle on the upper left corner of the web page?

It is the KAME project's dancing turtle. You can see it if you are connected via IPv6. OLSR.org likes IPv6 ;-) And OLSRd runs on IPv6 networks.


How do I send data packets in OLSR?

This is a common misconception: OLSR does not send datapackets it only sends it's own messages such as TC, Hello, HNA etc. These are sent and received and processed in order to find valid routes between mesh nodes. Once a route to a distant node or a neighbor is found and established, OLSR will simply set the corresponding kernel routing table entry. Hence, OLSR does not pass on the data packets itself, it only tells the operating system kernel to route accordingly.
Most routes are host routes.

Having lots of hoste routes, isn't that inefficient / will it take too much space?

Not really. A quick over the table calculation shows that even with an assumed kernel routing table entry size of sizeof(rt_entry) = 64 Bytes, we can easily accomodate 10k routing entries in 640kBytes of RAM. With these large mesh networks you might want to think of segmenting the network anyway.
So, routing table memory consumption does not have the highest priority of our development efforts.