I'm stressed about this topic since I use google adsense. My clics prices are going up in dollars (because french keywords are bid by Europeans I suppose), but the time between the clic and the conversion keep lowering my income.
Do you have any advice to limit this negative effect ? I think the obvious thing to do is quitting adsense for a 100% European ad system ?
Say you have a contract for $10000 USD due 6 months from now and the EUR/USD rate is $1.40 when you signed the contract. If the USD falls to 1.5 in those 6 months, you've lost ~7% on that contract, but if it stregthens to 1.3, then you've made a free ~7.5%.
Since you just want to make the contract and not play on the forex market, what you do is you open up a currency trading account and take the exact opposite position to the one in your contract. In your contract you lose money if the USD falls, so in your hedge, you open up a short position on the USD, such that you make the exact same money that you lost on the contract.
So once you've signed the contract, take a $10000 short position on the EUR/USD pair. If the USD weakens, you lose from the hedge, but gain from the contract, if the USD strengthens, you lose from the contract but profit from the hedge, so there is no risk to you no matter where the currencies go.
The downside is that you need the same amount of money to hedge as the amount you're expecting. One way to get around this is to use a leveraged trading account, however this restricts the amount of fluctuation your hedge can handle before getting a margin call - for example if you use a 5:1 leveraged account (that is, use $2000 to trade a $10000 position), your hedge will protect you against swings of close to 20 cents. So depending on how much money you have available to hedge and the amount of fluctuation you want to be protected against, you can choose how much leverage you want. (here's a tool to estimate it: http://www.fxtrade.com/tools/fxcalculators/margin_call_calcu...)
The good news is that with today's forex platforms, this is perfectly accessible/doable for any sized business/personal transactions.
Note: I do work for OANDA, but I'm just a developer there. I posted since I really do think currency hedging is neat. :)