いちごいちえ is a phrase I've heard especially often around adventurous, younger people. I think it gets kind of cliche and overused, but it's a great expression to throw into an enkai (drinking party) speech to impress an unsuspecting group of Japanese people.
Actually, Yoshie likes this one quite a bit and I think her former blog was called 一期一会.
Anyway, when you break apart the two pieces of this four-character construct, you have 一期 (lifetime or one's life) and 一会 （one encounter). The ALC rendering of the phrase is "Treasure every encounter, for it will never recur." That is the basic sentiment of the expression, but not quite as catchy and concise in English as it is in Japanese. While the literal meaning is a little different, I think the closest thing we have is "You only live once."