I suppose you could try to find someone that plays in the same worlds you do and make a deal. Something like: I'll dump FPs into your GBs on A, if you'll dump some on my GBs in B (minus a shipping and handling fee, of course). Might be an interesting strategy for getting rid of FPs in a diamond farm (which becomes a pain) and getting them into your main. I doubt it would really be worth the effort, but it would be a transfer of FPs between worlds. Sort of.