Lyocs take a feed from FAST for the unpaid stuff and from Overture for their pay per click results. On the PPC the top 2 are shown at the top of the page and the next 3 are shown at the bottom of the page.
Ask Jeeves take a feed from lots of places, mostly it's paid for traffic.
They have editorial questions results first (like "where can I find a plumber in London?")
Then they have websites they can show you which is the top 3 results from Espotting, then there are a couple of results from Overture US followed by the "websites I can show you". This shows the next 7 from Espotting (making 10 in total), some PFI results from Teoma, then some from DirectHit (which is also Teoma, confused? you will be), then the top 10 from Overture UK and finally the top 10 from Mirago.
So to sum up if you want to try the unpaid route then you can suggest editorial questions your site might answer. Then you can go to Teoma and do some paid inclusions (results will vary big time), then it may be beneficial to look at Espotting ahead of other PPC's if Ask Jeeves profile end users is the target audience you seek.
Hope that helps.
Trust me - it isn't!