Interesting - I haven't actually reviewed my Mac's config in a while - I might pick up a few goodies in those lists myself. For what it's worth, this is what I would automatically install on any new Mac:
- iStat Menus: RAM, network and CPU usage right in your menu bar. Ridiculously useful.
- Video player: VLC
- FTP: CyberDuck. Desperately slow to launch and not a big fan of the UI but it's free, it works and I use FTP rarely enough to never have bothered looking for something better.
- gfxCardStatus - not necessarily a must-have but quite handy to see which app is causing your Mac to switch to the battery-sucking discrete GPU.
- Email: MailPlane (gmail / google apps only). I have to say that I've never found what I would consider to be a great email client for my taste on either Mac or Windows. So these days, I stick with Gmail's web interface (which I'm not a big fan of either but there's no native app that I find any better).
- Text Editor: TextWrangler. I still prefer Notepad++ though (in part because TextWrangler, like so many apps on Mac OS X, is so slow to launch).
- DaisyDisk - for later when you'll inevitably run out of disk space.
- Parallels Desktop for Windows + Remote Desktop Connection to manage Windows servers. I wish there was a better RDP client and a decent SSMS-like SQL Server client.
- Apps that used to be must-have but that I no longer use: HandBrake (DVD ripping), LiquidCD (CD / DVD burning), NetNewsWire (RSS)
That's about it. Random stuff that you might or might not need: Acorn (simple, cheap image editor), CoconutBattery, Hues (standalone color picker), iStumbler (Max OS X's NetStumbler), MacHg (Mercurial client). You can try Sparrow for email too.
That's it - have surprisingly few apps actually.