Soon there will be a Forum on this site for people that want to trade tix.
The etiquette is exactly what you suggested...nobody makes money by selling there tickets or giving them away for the Face Value of the Ticket.
I am sure others will be looking to do exactly what yoiu would like or the opposite....
there are also other sites out there that have similar etiquette...I forget offhand, but I recall using one other U2 fan created site for such purposes.
Good Luck,
D