1. Secretive discussions between my wife and me without letting others know what we're talking about. This is more useful than you could imagine, especially when gossiping about people that are right next to us. This is less important in NE Philly, where EVERYONE speaks Russian. Unfortunately, my wife forgot French, but thankfully, we speak English, which is a minority language.
2. Chastising my child in public while not wanting other people to know what I'm chastising him about. I'm not entirely sure how this is advantageous, but I imagine it will be eventually.
3. Improved handwriting skills. When I was learning Russian, my wife would stand over me and make me repeat writing the same letters over and over again and slap my hands with a ruler every time I made a mistake. I now write in Russian better than I do in English (thanks, computers for hampering my handwriting skills). Also, my fingers ache when it's cold out.
4. Better interjections. Russian beats the pants off of english in terms of short, interjection phrases. I think my all time favorite interjections are things like "Nu" and "Vso", which mean "well" and "that's it" respectively. They sound so much more badass than anything we have in English. English, however, has other, cool phrases that have no equivalents in Russian, so I haven't abandoned my native tongue completely.
5. Inter-language puns. I love puns and word play, and it's even better when you sort of stumble upon something that's funny just through constant blabbering. Especially when it's inadvertently brilliant, then you get to take all the credit and be like, "oh yeah - I totally meant exactly what I said".
6. Awesomeness. You get that really cool feeling when you non-chalontly tell people, "what up - I speak more languages than you, mofo". Unless you're talking to a European, because, well, they speak craploads of languages. Although Spanish, Portuguese, and Italian essentially count as one language. Same goes for Russian and Ukrainian.
7. There is SOME value in reading books in their original language. For example, I read Les Miserables in French, and am working up the guts to attempt a Russian language book. Les Mis turned out to be infinitely more powerful in the native language. And I just read Kolobok in Russian. Totally changed my life.
8. When you're talking to someone who speaks that foreign language, and you no longer want to talk to them, there's no better conversation ender than, "I'm sorry, I don't understand what you're saying". Polite AND effective.
9. It's sexy. I know I've read about three hundred articles that say that bilingual people are super sexy, but I can't find them right now. But definitely google it, because it's true. If you go up to someone and say a bunch of crap in another language (even if it's something like, "there is a lot of poop in my underwear"), they'll swoon with ecstasy and immediately ask you on a date. Even if you're already married to them. Believe me, my wife does it to me all the time.
10. Reading foreign news. Because American News agencies care WAY too much about Marc Anthony and that other person. And Kate Middleton.