I've had some experience in creating excel spreadsheets to track data. I've created excel spreadsheets to track patient outcome statistics for a local hospital and have also created an excel spreadsheet for a nursery client to calculate a re-potting calendar (determining when a given species of plant needs to be re-potted to a larger container in order to optimize plant growth and, accordingly, nursery profits) and a few other excel based client solutions.
I mention this because in my experience you need to work backwards in order to come up with a given solution. In other words you need to determine what "output" you want (what types of information reporting you want to be able to extract from the software) in order to determine what data needs to be recorded and how it needs to be recorded. (I don't know whether or not that makes sense to anyone other than me).
So far I haven't heard of any software for land or lake management.
A couple of years ago I had a discussion on this very same subject with Bob Lusk. I mentioned that it seemed to me that someone should invent a temperature/dissolved oxygen/water clarity probe that could be placed in a pond and that would send information back to a computer (along the same lines as those weather station kits that you can purchase that will send information to your computer). This information could then be stored and utilized by the software.
IIRC, Bob mentioned that there were several companies exploring such a set up.
Note after an internet search I found a company that does have a wireless system to tract oxygen levels and send that data to a PC. Right now all we have is Dwight.
Special Note:
I'm certainly not criticizing Dwight, he is being much more diligent about tracking pond data that anyone I know. 
