Well, I know it's not uber-secure, but if I wanted that I would set up SELinux or something. I'm looking for something I'm familiar with and will offer better sandboxing than I have now without much work. Why won't Android do that? Is it Android's permissions system for apps? I would revoke unneeded permissions. Do you know of unpatched sandbox escape bugs that would allow a compromised browser to upload other apps' data?