Thanks Trevor!
DisplayFusion reminds me of another 'goody':
Synergy
"Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems, each with its own display, without special hardware. It's intended for users with multiple computers on their desk since each system uses its own monitor(s)."
The PDF ones put me in mind of another recent favourite:
gDoc Fusion PDF Editor
Lets you drag drop pages from multiple PDFs into a new one, edit, redact text etc. Handy if you need to be creative with your published expenses ;-)
- pay-for software, but you can try it for free. I edit/merge a lot of PDF in my job.
I agree with some of the others, must look at SyncBack. There's nothing on the list that really lights my fire though - cool yes, awesome, life-changing? Not being critical - it's a great list, but I'm really looking for awesome!