If you use a pocket pc platform like an iPAQ, GPX Sonar is fantastic AND it is free!! I can say that in the short time that I have been using the paperless approach, I have already found that having the previous logs is a great help!
There are definitely more people using Palm OS rather than PPC - but I still think it is extremely helpful to reference which platform you are working with - it can save others tremendous time and energy.
Cachemate works with Palm OS and not PPC
GPXSonar works with PPC and not Palm OS
PDA = personal digital assitant and is often also called a handheld.
Neither or these "names" differentiates between the PPC and Palm platforms.
Please do not misinterpret this as a lecture - it is meant only to help clarify the subtle differences that can be very confusing if one is beginning to explore this approach. My time spent in figuring it all out will have been well spent if I am able to help others along the way
As an iPAQ user and lover, I can honestly say that if one is considering using their PDA for geocaching, I would recommend the Palm OS platform. There are many more people using that type, many more software, etc. options available, and a great network of resources for questions, etc. At this point these are all limited for PPC users - something I learned after I had made my purchase and started using it