I use facebook all the time, and have it in English (Pirate). It's a fun way to waste time with friends when you're not getting together. I like sharing a photo from our latest party or whatever and reading people's comments, for instance. Also, it allows me to keep in touch with the people I've met accross the years accross the globe. I've got old friends from Switzerland, the US, Australia, Spain, Norway, Mexico, 3 different cities in Argentina, etc.
Plus, it's an excellent tool for keeping up with family far away. You look at their pictures, and their "status updates" (like Twitter, but with more characters)
Also, I'm friends with tons of groups and societies, so I'm always up to date with events and the like. That, and birthdays. Thank God Facebook keeps track of birthday without any input on my part.
I like how you can't be contacted by strangers unless it's by PM, or if you both comment on the same picture (which means you have at least one mutual friend, so it's probably safe)