The periodic table as a code
Every element has an atomic number and a one or two letter symbol, like 8 for O, oxygen, or 79 for Au, gold. Puzzle caches use this in both directions: a list of numbers that spells a word through their symbols, or a word you need to turn into numbers for a coordinate.
Enter numbers, symbols or element names to see them all side by side. To go the other way, switch to spelling mode, and CacheCrack finds a way to build each word from element symbols if one exists.
Example
32 8 20 6 2 is Ge O Ca C He, which spells GEOCACHE.