I've bumped so many times into the phenomenon of not being able to translate an apt phrase/word/something from English to Finnish (not to mention vice versa) that I just thought to ask you about your experiences. I'm lousy at explaining stuff so I give an example... There's a verb "jaksaa" in Finnish that I find utterly useful. It hasn't got an equivalent in English. And the other way round, the structure "A good few weeks" in English is sweet but I can't find a way to say it in Finnish. There are loads of similar ones that I can't remember right now, but the main point was to ask you to comment and post any similar things in any language. Because there's no word for it (please explain what the word without equivalent means, too) or because you think a particular expression is perfect for something etc.
"Jaksaa", by the way, is usually used in negative form. If you don't jaksa to do something, it means that you're too tired to do it or that you're don't want to do it because you're sick of it. It can also be used to say that you can't eat anymore because you're so full. (There's a word for it in Swedish at least.)
(X-posted here and there)