<p>Since I've started to use jQuery, I have been doing a lot more JavaScript development.</p>

<p>I have the need to parse different date formats and then to display them into another format.</p>

<p>Do you know of any good tool to do this?</p>

<p>Which one would you recommend?</p>

2014 update:
Moment.js
is an excellent date manipulation library, which includes parsing functions. It doesn't include automatic date format detection, but you can
specify multiple parsing patterns
.
Do you know the format of the dates before hand though, or are they user input?
A deprecated library for parsing dates is Datejs
. It hasn't been updated since 2007.