I live in Asia, and have for many years. Playing in currencies will take a lot of management effort, and probably not make you any money at all. There are two exceptions:

1- You leverage, and play Forex to buy $100 for $1. You can indeed make a fortune this way. You can also lose your total investment overnight.Not advise, unless you really want to make Forex your career.

2- You travel and live overseas regularly, or plan to do so in the near future. In this case, if your overseas residence is in the EU, for example, there might be an advantage to receiving some money in Euros.

If you, on the other hand, are going to live and play in the US, the margins on the exchange rates will likely wipe out any gain you make when you change your foreign currency back into dollars.

I live in Thailand and have taken an even bigger beating. A year ago USD bought about 42 Thai Baht. Now it buys 33, more than a 20% hit.

And me all the same! It is necessary to All to study to change together with the world.

Adsense income is only partly a dollar-income. For instance my Dutch visitors see Dutch adsense/adwords ads on my website. Those Dutch advertisers compete with each other, not with advertisers who pay in dollars. So the income from that quarter ought to stay roughly the same in euro's - even though the money gets converted into dollars and then back into euro's in the process. I do agree that it's wise to get income from a variety of places, but google is a global company and its ads are usually pretty local - if the advertiser knows what he/she is doing anyhow.