Fast Freeze is a jailbreak extension for iOS that allows the user to close apps much smarter with directly suspending them in memory.
Just install the tweak. There will be a section in the settings app to configure the activator action and stuff.
Compile it for yourself, use the .deb included or buy it in the Cydia Store for just one dollar.
You should know that. :P
Pretty much the BSD license, just don't repackage it and call it your own please!
Also if you do make some changes, feel free to make a pull request and help make things more awesome!
If you have any support requests please feel free to email me at shinvou[at]gmail[dot]com.
Otherwise, feel free to follow me on twitter: @biscoditch!
/