Can anyone point me to some good introductions on programming in a functional style for people who can already program in OO and imperative languages? My day j

Can anyone point me to some good introductions on programming in a functional style for people who can already program in OO and imperative languages? My day job is Java mainly with some javascript mixed in, did a lot of PHP too. I used to hate JS, untill I learned about closures (and libraries like mootools and jquery). Having functions as first class citizens is truly nice! I can see that the concept of immutability has a lot of value in a world where multicore reigns. And seeing code as data sounds like an awesome feature. But for me the question remains, how do I use it in practical everyday use? I mean, after 7 years of developing OO has ingrained to my mind. How do I transform that OO mindset into a functional one? Yeah, perhaps I've become lazy, but most tutorials I've found don't tell me anything usefull. They show me how to print fibonaci numbers. Great, but how many times have you needed to generate fibonaci numbers? I need to know how to sort a list, find your next connecting flight or make a transaction to deposit 100 USD on a bank account. I've build and helped design a couple of systems I'm proud of, even though I can see big flaws in all of them looking back. I've been most productive in garbage collected OO languages. I'm not willing to throw all that experience away but I am willing to accept that there are better ways to solve problems in code. I see great potential emerging from both JVM / Closure and .Net / F#. If anyone can give me pointers to resources which learn me how not to reinvent the functional wheel, but how to be more productive in my day-to-day job, I'd be deeply gratefull.