How about CCleaner acting like an install manager. Let's say... you downloaded a .exe file called uhh Spybot.exe or something and had it in C:\Downloads\.
Then you right click on spybot.exe and click on Open With CCleaner and CCleaner will scan the registry and files and folders on your computer and then install spybot.exe and then scan the registry and files and folders again and next time when you want to remove spybot from your computer. All you do is open up CCleaner and uninstall it. This will uninstall it completely.
There is a program called Total Uninstall 3 that does that, but you have to pay for it. There are also other version but again, you have to pay for it. If a feature in CCleaner like this was available, I'm sure A LOT of people would download it.
Hope this is helpful!