I didn't study Latin at school, although I wouldn't necessarily say this has put me at a disadvantage in life. Learning French was hard enough, but at least that's a language I can use. Much to my genuine surprise then when I first came to Germany at how frequently certain set phrases in Latin appear in an everyday context such as the written press.
Quo vadis - or, "Where are you going?" - is one that's always puzzled me. Thanks to my knowledge of French, I was always aware enough to realise what it would roughly mean. However, the phrase seems to crop up everywhere, though most commonly in German-language newspaper headlines, and I increasingly get the impression it's plonked in there because the headline writer is too lazy to think up something more original. For example, you see an article about FC Basel - for example, an analysis looking at what the remainder of the season holds in store for Switzerland's best supported football club. The headline would look something like this: "FCB - Quo vadis?" I think it's safe to say that that sort of thing is not done by Fleet Street journalists.
Carpe diem is another one which appears a lot here in Germany. It's one of those terms Germans like to use in English, but which usually illicit blank looks on the part of English native speakers. In fact, I had to look up its meaning again (i.e. "Seize the day") just now in that, ahem, authoritative Internet resource, Wikipedia. " It has a nice meaning, though, I must admit. "Carpee Dee-em!"