3. Bitcoin / Swipp exchange service. Where each masternode can offer different exchange rates, competing with the other nodes when exchanging currency back and forth. Theoretically, it would even be possible to offer multiple currencies, with Swipp as a base currency. This will require each masternode to hold copies of blockchains from several currencies.
It's interesting idea. But it requires not only copies of blockchain, you need to freeze coins for future exchanges on some wallets.