But concentrated on the simpler tasks. Rosetta Code has examples for Gaussian Elimination, but no string to number conversion. It also has some really esoteric languages. It's really more of a Rosetta Stone, while Programming Idioms is more of a lookup for the typical but infrequent stuff you (well, I) tend to forget when working in multiple languages.
you want to be known as the one who invented the wheel, because it looks good as a resume item. That's why the wheel keeps getting reinvented again and again, and usually quite poorly.