We have our site set up in 4 languages and have specific German language AdWords for German search terms.
One thing we have found after having a website since 1999 is that many Europeans speak some English and read more English. If they are looking for a product that doesn't have a specific foreign translation then you can just run with the English language ad.
If the search terms are language specific then just set up separate campaigns and geolocate them to the countries you want to reach.
If, for instance, there are specific German search terms set up a campaign with those search terms with a German language ad and geolocate it to Germany, Austria, Switzerland, etc.
Be prepared that if you advertise in a foreign language you will get e-mails in that language.
I was thinking of that.. I think I can find some ways around this...
So basically your landing pages and site is in the foreign language, and the campaings are in english. How would I translate my keywords from english to the given language? I found a site that does it for free, not sure how accurate it is, but its worth a try.
Also, if you wanted to SEO your site, how would you do that? If you were doing link exchanges, english sites would be no good correct?
If you have keywords that are worldwide accepted, such as "GPS", "DVD", etc, and you create ad copies in different languages targeting foreign markets, you have to use them in seperate accounts. Otherwise Google will show the ad copies alternatively to all the countries you have selected.
Ideally I'd "give" them the site as their business in a revenue partnership (with a performance goal). It can be quite a bit of work (as you know) that a non speaker just cannot do well.
I haven't put it together at this point, so it's just an idea!