I recently purchased a Macbook (13") and have been perusing various blogs and zen/hacker sites which provide insight and instructions on becoming a proficient user. I feel relatively comfortable on it, though not quite as comfortable as on my native OS (Linux).
One thing I keep coming across is Quicksilver. Most productivity tips include utilizing this application for more extensible app launching, and better system navigation. I've used Launchy extensively on my Linux systems (and my Windows box at work), and I wouldn't say it's revolutionized my work flow.
I've been using Spotlight since it came with my Mac. Are there compelling reasons to switch to Quicksilver?