Some years back I taught the Beginning JavaScript at Cañada College so here are a few scripts I've come up with for that course:

Cubes

Find Ramanujan's Taxi Number (using JavaScript)

Latin

Generate Pig Latin (using JavaScript.) Default text is a quote from Mark Twain.

Triangle

Solve the Prime Triangle (using JavaScript)

PrimeSpiral

Generate the Prime Spiral (using JavaScript.) Much slower than the my Java version over in my Java Applet pages.

SubNetwork

Calculate SubNet Tables (using JavaScript.) Based on similar tables in CCNA For Dummies

WordPlay

A simple word game (using JavaScript.) Starts with one four letter English word (eg. 'word') and tries to reach another word (eg. 'play') via other valid English words by changing only one letter at a time.