A small ruby app that prints a multiplication table of prime numbers.
It uses a simplistic incremental Sieve of Eratosthenes algorithm to find primes based on this academic paper: http://www.cs.hmc.edu/~oneill/papers/Sieve-JFP.pdf
Instructions
> gem install primetable
primetable 10
This will print the first 10 prime numbers. You can try raising that number and seeing how far you can go.