@wkempf: That Flash one nearly caught me out the other day on my W7 netbook. Thankfully I was able to cancel it before it had downloaded Chrome, Google Toolbar and who else know what. Normally I'm careful enough to deselect all those kind of things, so I suspect it been even more devious in stealth hiding that option. Java, however, has not been installed on any of my machines for a long time and I find I'm a lot better off for it.
@Bass: +1 to not using software that does this.
Flash was always a git, because it's still difficult to use the web without it and there never was an alternative. Switching to Windows 8 has resolved that though and my machine is more crapware free than ever!
@kettch: I'm hoping that's what we'll see in Windows 9. Solving the problems of isolated installation of desktop applications without constraining their ability too much (as well as needing to live in the same world as old-school Windows applications) is no doubt a difficult goal, but not unattainable either.