I have no idea why you would want to keep track of your heart rate if all you’re doing is sitting idly by the computer. Seriously, how much faster can your heart beat if all you do is type furiously on the keyboard? I suppose this is interesting to see whether your pulse races whenever you check out NSFW images, or it might be interesting to see if you can remain calm whenever the stock markets plunge. Inside the Vit W1 mouse lies a pulse rate sensor that will send collected information to your computer wirelessly, where a pre-installed software on your computer will interpret whether you need medical attention or not by displaying a corresponding emoticon on the screen. The mouse is accompanied by five buttons, a small USB receiver, 1200dpi sensitivity and a maximum working range of 30 feet.
Source: EverythingUSB
The reason why this might be usefull is not bpm like other exercise monitors i.e. Polar.
But a biofeedback hrv(variability) that, rather than sensing how stressed your body is, measures how stressed your mind is.
There is a far bit of study showing how this can help people with angina/hight blood pressure/anxiety disorder etc. Although in an Orwellian environment it could also be used to monitor staff, or produce games that are able to sense how excited you are by different things, and modify its self accordingly. etc..