From the blog:
size_readable() converts a number of bytes into human readable form.
str_highlight() provides a variety of text highlighting options for plaintext or HTML strings.
tab2space() converts tabs to the appropriate amount of spaces to preserving formatting.
Cycle provides a novel way to iterate through an array. This is commonly used for zebra-striping tables.
str_chop() provides a number of options for trimming long text into something suitable for display.
hex2rgb() converts HTML hexadecimal colour codes into their RGB equivalent
array2table() allows you to quickly display the contents of an array as a HTML table. It can also recursively display data for nested arrays.
dirsize provides a heavily optimised method for calculating the size of large directories.