ActionBoard adds cool system functions to your Appswitcher toggle. SBSettings like functionality on the bottom of your screen such as respring, reboot, power off, and compose. Action board also adds another row of commands to your Appswitcher for SMS, mail and Twitter. Selection will allow you to compose a message quickly.
No new icon will be added and there is nothing to configure in your extensions. ActionBoard is available Cydia for $0.99.