Just got a macbook pro too - a few useful apps:

- iWork '08 (for keynote alone and fast launching of Office docs)

- Think from www.freeverse - to avoid distractions

- Adium for IM

- Twitterific

- Airport radar widget from http://www.macwireless.com/

- Mindmanager for Mac 7

- Fusion of Parallels with XP (not Vista)

- Thunderbird for email (Mail has great search, but is unreliable IMO)

- Pocketmac to sync your blackberry (if you don't have an iPhone)

- Anti-Virus (if you feel you need it) - Sophos Small Business Edition is reliable and lightweight

You also may want to see this post on Chris Pirillo's top 100 mac apps: http://chris.pirillo.com/2007/11/06/top-100-mac-a...