I've just noticed that this thing is covered with oil, what is it? I feel dumb, sorry to have to ask.

Power steering pump.  There's an oring in the plastic fitting on top.  Get from the dealer.

Very cool. Could I just order the O ring and fix it myself?

assorted o-ring pack from autostore works fine

Heck yeah!  It will leak a bit during the repair so have some rags handy.  Just keep the fitting elevated some and it will drain into the reservoir.  That plastic fitting can break so check for cracks.  Get a old toothbrush and some mineral spirits before the repair to just brush off the top of the pump.  

You guys rock, thanks.  I haven't had to fix our Sooby in so long that I forgot what was what!