Traveler IQ Challenge
This game varies quite a lot in difficulty, because for much of it you can be successful just by getting the country right (i.e., you don't need to know where Dublin is within Ireland, so long as you know where Ireland is). Then they start hitting you with the Oceanic states and minor cities in Russia which you can easily miss by 4,000 miles. So far I've been unable to get past level 11.
Not a lot of replayability, though, because there's not a large database of cities.