[jmduke]

It's certainly not comprehensive, but here's the shortlist of stuff I make to try out a new language, in order of increasing complexity:

-- Sudoku verifier

-- library generator (scan all of the music files on your drive and compile a list of artists)

-- dictionary app (using Wordnik API)

-- flexible calculator that can detect postfix v. prefix

-- Sudoku solver

-- Hidato solver (which is essentially King's tour, but cooler)

-- tumblr API wrapper (or really any OAuth service)

-- n-gram language classifier

[vineet]

Thanks for sharing. My list has much more CRUD apps with different UI challenges (like a single person todo list).