I use Hivenotes by Apimo. It's a freeware program that meets most of my immediate needs. It has the ability to sync with a Palm device, but unfortunately, my PDA runs on MS Pocket PC2002. So I scribble my notes in the field on paper and transfer to the computer later. And I haven't yet figured out a way to print a hard copy of my entries, which I especially don't like. But it is free.
There was another commercial program I downloaded a while ago, but I couldn't make sense of the trial version, so I deleted it after a while. I haven't been able to find any other programs out there.
MS Excel is good for keeping track of honey yields catagorized by hive numbers, dates, etc., and displaying them in easily readable charts.