I"m biased but here are the things in ODNT I use constantly:
Keyboard Launchpad. Not enough good things can be said about this. It can dramatically improve productivity. It's $10 on its own.
WindowBlinds. It's $20 on its own.
DesktopX. It's $20 on its own (will be going to $24.95 in January).
IconPackager. It's $15 on its own.
IconDeveloper. Another killer app IMO. I've not traditionally been an icon creating person but now that it's so easy to do it, I find myself making my own icons regularly. It'll be $20 on its own.
SkinStudio Pro. I use this very regularly to tweak skins I download. Most skins aren't quite the color I like. It's $30 on its own.
Theme Manager (WinStyles). I use this to apply suites as well as save my desktops. It's $10.
So right there that's $125.
I use other parts of Object Desktop as well quite regularly but these are the ones I use constantly. I occasionally use WindowFX, ObjectBar, Tree View, ObjectZIP, DriveScan and a few others.