Microsoft Bluetooth Notebook Mouse 5000. Response is excellent, size and shape are just right (for me at least), battery life is excellent, and the price is right (as low as $25 online). Find It Online with Google Products
If your notebook computer doesn't have built-in Bluetooth like mine, you can get a Bluetooth dongle so small you can leave it plugged into a USB port, like the Kensington Bluetooth USB Micro Adapter, or a much less expensive generic equivalent.
If you prefer a larger mouse, check out the other Microsoft Bluetooth Mouse options -- while I haven't used them, my guess™ is that they work equally well.