I just googled for FileMaker 7 custom functions and found Brian Dunning’s nice little database of free custom functions. There are 121 right now. Here are some quick favorites:
Color (text). This custom function has about 150 pre-programmed colors in it and also will handle hex colors if you lead with a # symbol. Geoff Coffey.
CreditCardName ( CreditCardNumber ) Based on Brian Dunning’s Card Validator, takes 15 or 16 digit credit card number with or without dashes and returns the card type. Also checks for validity. Geoff Wells.
MoneyToWords(NumberField). Takes a numeric value and converts it to words for a check. Example: 1234.56 = One Thousand, Two Hundred Thirty Four Dollars and Fifty Six cents. Don Wieland.
RightPosition ( text ; searchstring ). Shows everything to the right of the search string in text. Example: RightPosition ( “thequickbrownfox” ; “quick” ) = quickbrownfox. Bob Shockey.
You can copy and paste the full formulas for these custom functions into your own custom functions. Check this out!