Any way to keep background apps in background??

I tend to be a power user and probably like most people
out there always have multiple applications and/or
browser windows open simultaneously. Windows is great for
this. My one big gripe, though: background apps popping
up and becoming active.

Is there any kind of tweak or utility that allows me to
fix this? I want whatever process I'm working on in the
foreground and for it to STAY in the foreground no matter
what other programs are doing in the background. (This
is especially a problem with multiple browser windows)

Any help is greatly appreciated!

THANKS!