The following are mostly-useless tools that I've put together at some point or another.
Convert a UNIX timestamp to an English date or vice-versa.
Convert a Roman numeral to Arabic or vice-versa.
Convert an integer into its English equivalent.
Coin flip simulator, for those times you don't have a coin on hand.
Check to see if a string is a palendrome.
Check to see if one string is an anagram of another.
Determine when a loan will be paid off. Slightly incorrect.
Enter a pair of birthdates to find the date when the first will be twice as old as the second.
Shuffle the order of the lines in a block of text.
Enter a set of names to generate a randomly-drawn list of who should buy for who at Christmas.