I came across this JavaScript regular expression a while ago that uses regular expressions to create excerpts from a larger block of text. You can specify the number of characters in the excerpt by simply changing the second value within the braces in the regular expression. For example use {1,55} to create an excerpt 55 characters long or {1,101} to create an excerpt 101 characters long. Of course the best part is that the phrase will always truncate on a whitespace character!
var s = "This regex can be used to break a long ";
s += "line of text on a full word. The qualifiers ";
s += "specify the minimum and maximum number ";
s+= "of character allow before the break and can ";
s+= "be changed according to your needs";
var result = s.match(/^([\\s\\S]){1,30}([\\s\\.])/)
document.write(result[0] + " ");
I cannot remember where I got this from, but thought that I would share it with the community as I have found it to be extremely useful.