When I first learned about number bases, I thought it was neat that some numbers happened to correspond with real words. Here's a cute little encoder that uses that idea.
Take a text input from a-z, and read it as a number. Figure out the minimum radix (base) needed to properly read it. Convert it to base 10. To 'decrypt', provide the original base and the base 10 number.
For example, 'radx' is 1073243 in base 34.