Best Features?

i own a Macbook Pro and an iMac, i'm really enjoying them both at the moment and just wondered what else i could do on them?

What are your favourite features on your Mac, any really useful shortcuts, tips and key commands?

Any help is great, Thank you.

There's a ton of threads on these topics. Have you tried using the forum's search features and looking at the sticky threads at the top of each forum?