I normally create a Pocket querry for my area twice a week and have it downloaded in my Ipaq (as an e-book) and my Magellan 315 (as an easy GPS file) at all times. then if I want to suddenly go for a find at lunch or between meetings, voila! I also do have a GPS receiver for my Ipaq and the use of Streets was adequately covered by a previous poster. I do have a routing software (CoPilot) that routes well, but neither allows the inputting of lat/long coords. The neatest use I have found for the Ipaq is wireless webbrowsing to geocaching.com and as a data-entry device (for which I guess most people use an older technology called "pencil and paper."
The neatest use I found was when I was planning an 18 cache day in the city of Washington DC. They were all virtual (keeps the Secret Service a little happier) so all had questions that I had to answer. I downloaded all of the caches and copied and pasted all of the questions to a Word Document on the Ipaq. I went to my 1st cache (20 degrees and windy) and took out the ipaq to write the answers. My fingers were so cold, I was about to give up the whole idea, when I accidentally pushed the sound recording button. this allowed me to record the answer as a wave file embedded in the document. GLOVES COULD STAY ON!!!! I finished all 18 in anout 3 hours and type the answers into e-mails from the playback of the waves. That was pretty cool!