I've been doing some research into the regulatory side of things, because I continue to be dumbfounded by the number of untapped opportunities, even beyond those you've already mentioned.
What I've been finding out so far is:
1. Regulatory and Oversight - is less restrictive in the US than Sweden, but since
EU is based there, the more restrictive requirements apply. This could be circumvented by having servers in the US (and other countries as well), but could generate a tax liability (or two), as well additional overhead costs (such as FDIC Insurance for US-based).
2. Operating as a "Credit Union" would have less regulatory concerns, however credit unions have little standing in multi-national financial networks.
It might be the better route to do something akin to this, and thereby circumvent tax laws*, regulatory restrictions and oversight committees, as an LLC (Limited Liability Corporation) making investments in established, offline investment firms, and paying interest privately, with the initial tax liability falling on the LLC.
However, to make this sort of "private investment banking" workable, contracts would need be drawn and signed by all parties involved, to ensure the enforceability of applicable local and international policies.**
* Circumvent, in this case, is not intended to imply any form of tax-evasion, but rather a means of limiting the tax liability to a single entity for sake of day-to-day operation.
** Hence the move to a one-world currency, while convenient, is a near-impossibility due to - yep, you guessed it, one too many lawyers.