Is there an application manager that would easily
- kill/close an application from memory
- install applications
- unstall applications
Platform: HTC Desire and Android 2.1.
If you are running Android 2.1 or 2.2 you do not want to use app killers. It actually hinders performance and could cause more problems because Android has built in app killing functionality into the OS.
No app currently exists that can do all three of those. You can get an app that can do the first one, there are lots of those but I wouldn't recommend any of them. Or you can get an app that can do those last two...
I agree that it could potentially cause problems (I've only had one problem app [SportsTap used to give me a pop-up when I'd force-kill it], and that has subsequently been fixed), but they definitely have their place. Sometimes I want to kill everything possible in one fell swoop because of a problem with the app. For example, the built-in newsfeed widget sometimes messes up my touch screen, and killing it corrects my touch issues.
Nonetheless, I'm using TaskPanel these days. As Webs said, it doesn't do install/uninstalls, but since he covered those, I figured I'd recommend my task killer of choice.
ASTRO file manager does all those things, although I have to agree with Webs and say that you shouldn't use task killers as they are no longer needed. For more information, go to Application Fundamentals and scroll down to component life cycles.
Just trust the system, the way Android is designed means you don't need to do memory management, the OS does it for you. Even the developer of Advanced Task Killer said in an interview that his application is no longer needed.