A good overview on planethunting and why technological civilizations may be rare in the Universe. (One reason: They may not be very long-lived on a cosmic – or even planetary – timescale.)
The search for life in the universe is valueable in itself. At the very least, it is a reminder of how incredibly precious life and this living planet is, and it helps us (mentally) place earth and humanity in a much larger context.
(SETI is also one of many mirror for us, although what I can say about it is just the same as in other posts.)