I also like the site a lot.
From a usability perspective, I believe that the Date fields should only have validation done after the cursor leaves the field. Personally, I am used to going in and changing 07/26/2010 to 06/23/2010 by simply clicking within the month, backspacing and typing in a 6 where a 7 was. It seems that the code tries to validate/correct it on each change in the field, which creates a big mess when you try to do it the way I described. Effectively, to change a date, I have to remove the whole original and retype it all again.
When I tried to put in several inspections, the second inspection pulled in all of the data from the first one, as I was trying to enter it. This created a problem on some of the second and third windows, as some of these items were radio buttons and there was no way to deselect the options completely. I would assume that closing my browser would fix this, but it would be good if the data was cleared out on successful save.
For an upgrade function, it would be nice if there were a way to track a few bits of your own metadata, that you as a beekeeper could maintain. Having a page where you could enter metadata and then having a page for each hive where you could check those bits that were relevant to that inpsection, would be great. An example might be that I could enter the following items : Fed 1 Gallon Syrup, Fed 2 Quarts Syrup, Fed Pollen Patty, Fed Dry Megabee, Took Frame of Brood for a Swarm Catch/Cut out, Moved old frames to outside, etc.. Then, these would populate a form on the inspection sheet and allow me to check what I wanted for each inspection (and I could go back and add more, delete old ones or edit existing ones at a later date.)