Upload & Sell: On
I've had several and this is the one I was most recently using: TrueDoF I like that it gives me a reminder about when diffraction softening will start kicking in.
Not the original question but I sucked it up and payed $29 for pCam Calculator: http://www.davideubank.com/Good_Focus/pCAM_Film+Digital_Calculator.html It's overkill for most people and some of the programs it contains are basically for video, but it gives me a lot of different calculators including DoF, conversion tables, Dimensional field of view, Macro shooting distance, light coverage, even turns my iPhone into a Siemen's Star chart. So I don't carry a dedicated DoF calculator anymore.
And I don't work for them, know them, or anything else like that. Just impressed with the app.