I had some time on my hands and tried to spend it usefully (learning Python while actually doing something useful). So I wrote Depth of Field calculator that runs on Python enabled Symbian phones.
Ok so the usefulness part is so so, it is only useful if you are interested in photography and actually try to calculate the DoF instead of just going for it. While most of the time I just go for it, there are times when I can't really tell by the picture on the screen how much of it is actually sharp and where does the blur begin.
Here is what the result looks like on the phone screen:
The files are available here.
And if you want additional information on Depth of Field and formulas used in my prog look here.
If you like it - drop me a note - leave a post on the blog. If you want more/new/different features - please don't hesitate to ask - I'm sure there is more to it than just what I did.
PS: the code is my first try of actually doing some Symbian stuff in Python so please keep the comments objective ;)