I work with computers, primarily database. The only thing I can't do remotely via the internet is shake your hand.
There are also a lot of small 'fix this specific problem' websites out there where people and companies list jobs and take bids on them; again related to databases.
Keep in mind that most countries have serious problems with foreigner's coming in and working. It helps if you don't actually make any money in
those countries, being paid via the internet helps.
Heck, having internet on the boat helps