Anyway, keep in mind that this list is biased towards my specific needs, primarily 64-bit, KDE, and apps that I don't hate *coughTransmissioncough*.
Many of the apps I use are cross platform, so I didn't even need a replacement. Of course, some of them have actual better alternatives, but here are a list of apps that are cross platform.
- 7-zip (support for 7z compression, either with FileRoller or Ark)
- Dropbox = kfilebox (for KDE, without Nautilus)
- Foxit Reader / Adobe Reader = Okular
- Pidgin = Kopete
- Xnview = Gwenview
- Amazon MP3 Downloader = Banshee
- Auslogics Disk Defrag = Linux!
- Clamwin = Linux!
- Dexpot = Linux! (KDE/GNOME/etc)
- GSpot = MediaInfo
- HiJackthis = Linux!
- ImgBurn = K3B / Brasero
- Magical Jellybean Keyfinder = Linux!
- Musicbee = Banshee
- PDFCreator = CUPS-PDF
- Q-Dir = Dolphin (or PCmanFM / DoubleCommander)
- Revo Uninstaller = Apt/yum/etc
- Speccy = HardInfo
- uTorrent = Ktorrent / Deluge
- WinDirStat = KDirStat
- WinSCP = FileZilla
- AdvancedDiary = RedNotebook
- Autoruns = Linux! (GNOME/KDE/etc)
- AwesomePhotoFinder = DupeGuru Picture Edition
- CCleaner = BleachBit
- FastStone Capture = Shutter
- Programmer's Notepad = Editra/MadEdit/gedit:kate/QScintilla
- Project64 = Mupen64Plus+CuteMupen
- Teracopy = Ultracopier / MiniCopier
- TinyCad = KiCad
- Zoundry Raven = Blogilo
Unfortunately, there are certain apps I just haven't found a good replacement for, some of which I don't think I ever will. But I have found some possibles, which I'll list.
- Amazon MP3 Uploader
- Autohotkey = ~AutoKey / ~IronAHK
- Recuva = ~TestDisk
- ResophNotes (SimpleNote sync is critical)
- Wallpaper Master
- Windows live Photo Manager = Kdenlive / Shotwell / Lphoto
The best part about this is that pretty much all of the apps that I absolutely need are on the top two lists. It's only some of the minor apps that I'm having trouble finding replacements for. And some of them just need some good tweaking to get working. (Mupen64Plus worked when I tried to fire up Ocarina of Time, but CuteMupen keeps crashing on me. Maybe I can write a GUI for it in Python+Qt.)
The real nicest part about it is that it's not just that Linux has alternatives, it's that KDE has alternatives that seamlessly integrate into the environment. I'm beginning to see why Mac fans love that seamless integration, because KDE pulls it off quite well, and Windows and GNOME just don't.
Hope this might help someone or something.