Fun
Coin flips, name generators, star signs and the odd metronome.
Tools under no particular obligation to be useful, and a few that turn out to be anyway. It is worth being clear about which is which, because you cannot tell from the names, and the difference between a party trick and an exact answer is the sort of thing a page should say out loud.
Entertainment, and the ones that are not
Numerology, the mental age test, the life expectancy estimate and both zodiac calculators are entertainment. Each applies a stated rule to what you type and returns a consistent answer, and each page says as much: a life expectancy figure built from actuarial averages describes a population and knows nothing whatever about you. Read them as party tricks and they are good ones.
The rest are exact. The sudoku solver either finds the unique solution or tells you the grid does not have one. The BPM calculator and the tapper measure real tempo and musicians use them. The decibel and wavelength converters are physics with one right answer. The tier list maker and the bingo card generator produce something you can print and hand round, which is why they are here rather than under Business with the other document makers. Coin flips and dice are Random; name generators are Text.