Musipedia is an editable encyclopedia of musical themes. It can be searched by entering notes or tapping a rhythm. Melodies can be identified even if the melody or the rhythm is all one knows.

The Crossnumber Puzzle Solver is an interactive constraint solver for number puzzles.

One can solve existing puzzles, create and solve new puzzles, share them with the world, or buy books with puzzles.

On IBAN-BIC.com, one can calculate or validate IBANS, bank account numbers, or BICs. With SOAP interface and correctness guarantee. Data are checked for updates every day.

SaferSignup e-mail aliases allow you to give a unique e-mail address to every untrusted communication partner who might sell your address to spammers. Once spam arrives on a particular alias, just block it.

XML Validation: An online tool for validating XML/XSL/XSD files.