I have a Synaptics cPad on my Toshiba laptop and really enjoy it. I've had no major issues with it. In fact, the applications that are launchable within the "pad" itself are handy - calendar, calculator, sticky-note, etc. The only one I dislike is the signature-capture. As mentioned above, pens, etc, do not work. You ever try to sign your signature with YOUR finger-tip? Besides this annoyance, it's been great. (Any "signature" suggestions out there, cPad users??!)
Options with the cPad include "Tap-and-Drag" (which I dislike mainly because I think mine hasn't been set up properly...or this may just be a flaky feature that I found not user-friendly), plus "Palm-Check" where if you accidentally place your palm on the pad it ignores that), and also vertical and horizontal navigation drag-bars (which are very handy when moving around on web-pages). It also has zoom and pan abilities, but I haven't tried, or even programmed them "on" yet.
One other option the cPad has is to display dual time-zones. I have it always showing the local time where we reside, and the home-town's local time. Handy when deciding to make a phone call, etc.
There are applications that can be launched within the cPad that are either downloadable or programmable...neither I have gotten, so I cannot comment on this feature (I'd like to try some things, though, but just haven't located any worth getting yet!) Also you can put custom logo's or photos (grey-scale) too, but once again I haven't tried this.
Strangely, the cPad isn't on current Toshiba laptops I see for sale, even though this has been a great product (9.7 / 10 IMHO).
Synaptics, the maker of the cPad, even has a speaker-pad product (no comment as I haven't used it).
Here is a good cPad "how it works" site:
http://www.synaptics.com/technology/tcps.cfm
Cheers,
R.D.