OmniStat is a free tweak available on the BigBoss repo in Cydia by Mathieu Bolard.

This tweak is a Notification Center add on that displays useful tweaks and toggles.

On the main page, displayed is the name of your device, the model, the OS version, the build number, the amount of storage, and free and used space.  Along the bottom there is a toggle menu that can enable and disable essential features such as Wi-Fi, airplane mode, bluetooth, and location services. There is also a power menu to kill background apps, restart springboard, reboot, and shutdown.  To the left of that there is a menu with links to the developers Facebook, Twitter and a donate page.

Swiping to the left, there is a page that includes network and battery information. Items like your host name, Wi-Fi IP, network name, cell IP, your MAC address, battery percentage, and charging status are displayed.

On the next page, there is memory information including a colored pie chart displaying RAM usage in a visual format along with the text to the right of it with the amount of MB free in each category.  Tapping on the chart will free memory.

On the last page, your process and UDID are displayed.  Your process list displays the name and the PID although no way of killing them.  The UDID is only displayed but a copy button is included for convenience.

In summary, OmniStat is a simple widget to display essential and useful toggles and system information.  I do recommend this to anyone with a jailbroken iDevice.