Question:
He will only need to call UK, France and Germany.

Is there a Superline / Onetel equivalent out there ?

Answer:
Is there a Superline / Onetel equivalent out there ? if he wants something like superline / onetel yeah there are quite a few over in America.  There is one he can get from British Airways magazine.  Also since he is going there for a year he might be able to get package deals.  But at least with UK and Germany it might actually be cheaper for the people he is going to call,to call him instead. Since there are call through services which allow you to call USA for example in UK with Everyday 50 (on Orange) and only pay 1p per minute for the call.

-Anyone got anything any cheaper I guess it will be hard to beat 1p -rate we get here in the UK ;-)

Going to be very hard to beat, hence why it might be better to just get them to call him up :-) or even setup before he goes a callback system.  (and the orange mobile calls one of these call through service and than call him in America and than call the person in UK and make a conference call.

But that makes it 2p a minute and hence might not be worth the hassle in this than :-)  (But seriously there do anyone know what software you need to make a computer answer a call on either mobile or landline and than dial other number, and pass the call through it? if possible?

Well back to your problem above.  Well one other solution he can do is get ADSL / Cable modem / Lease line where he is going.  

He can than use this service it is VOIP but I think on broadband connection it is quite good.