MiniUsage displays various data like CPU usage, amount of network flow, battery status and process names which uses much CPU time in a menubar. It takes little space and can display various data, so it's suitable for notebook.

While the application is running, this information can be referred via AppleScript.

Note from the developer:
This software is "Donation-ware". If you want to continue using it, please make a small donation to help the efforts for the Japan earthquake and tsunami disaster. (For example American Red Cross) It doesn't imply any donation to me.

Please note that the author takes no responsibility for any damage caused by the use of this software.