Like, lets say for example that I didn't think that jeanie3 was pulling her weight in the 'being interesting' category. I think that I should be able to offer her up on the open market in trade for someone else who might beter fit the rest of my friend-list 'team'. This would allow people to better customize their friends list and search for people to fill vital lynch-pin positions that they might currently be missing. Maybe someone feels they need more support, so they could swap for someone high on compassion. Or perhaps what you feel your LJ needs is a bit of color and spash, so you can trade for someone who'se a bit of a wonk and exciting.
Not to mention that this would also give employment to a whole buncha number crunching flaks as each person can be reduced to a set of statistics which will quantify how valuable a commodity they are as a friend. There would be categories such as: average # of entries/comments per day, emo rating, meme %, etc. I'm sure there would be some number fudging and perhaps over time, even a scandal like someone hiring ghostwriters in order to improve their stats. Sort of like steroids for MLB players.
Overall, it seems most friends lists are too inbred anyway. It'd be nice to have a case where you could really intermix things a bit and hope your new acquisition betters the team....or if nothing else, reduces your Canadian ratio :P. Who says you can't buy and sell people.