OK, back to original topic : a bag full of stuff that can help you in most hard circumstances.

Although e-gadgets are not reliable in hard times, but I am fan of software applications that help tackle different tasks. One example is unit converters. They are life savers sometimes when you need to know something and you get it but in the wrong units. You want to know the BTU's , but you get your info in kilowatts, for example.

Do you know any other kind of software or application that is also helpful. I don't mean nice to have like a visdeo game, but really important when you need it.