I'm interested in designing a gadget that lets you gauge the environment easily, and it would also have some other nice tools ontop.
>thermometer
>hygrometer
>compass
>aquitaine sundial
>fire-starting magnifying glass

The thermometer would have a copper heat-sink to quickly equalize to air temp.
The compass could go a few ways, but any basic magnetic compass would do well enough.
The sundial would have a set of replaceable rings depending on your latitude.
I think for the magnifying glass, it would be about 4 inches in diameter, I'd have to see about the levels though.

The device isn't made to be super slim, but it is suppose to still be easily portable.
What other things would be great for a device like this?