Can you name the applications you used (couldn't use) on Windows 7 that had compatibility issues with the operating system? (One application per answer please.)
Daemon Tools current has an issue with Windows 7. There is apparently an updated driver floating around to fix it, but it's not part of the standard install right now.
DVDFab - Will periodically result in a BSOD, however if you run in compatibility mode for Windows XP(SP3) it will work fine.
Starcraft tends to hang the system for no apparent reason at times. Was that way in the Beta and continued to be so in the RC. DOn't know about RTM. The funny thing is, everything else still seemed to work (I could still talk on Skype, although admittedly Skype is as evil as you can get) but no input whatsoever seemed to work anymore.
I didn't try killing the game from remote, though.
So currently I'm using a VM with an ancient Windows to play in :)
Miro (http://www.getmiro.com/) doesn't work correctly. Video playback is blocky and pixelated. Other player (WMP, Media player classic) work well. Tried to update the graphic driver but it still doesn't work
Pretty much all anti-virus software doesn't work, and will need a new version with Windows 7 support to work. I've used both McAfee and Symantec on Windows 7 for work, and both have major issues on Windows 7. McAfee randomly causes a BSOD when doing an on-access scan, while Symantec causes a BSOD at boot. I've heard most other virus scanners have similar issues, although I haven't used them.
The KMPlayer doesn't seem to work well in Windows 7 Ultimate 64 bit.