There are a lot of <a href="/dev/web/design/color_choosers.html">color-matching tools for visual designers</a> available, and many of them are suitable for coming up with an outfit.  Ones I particularly like for clothing include:

<ul>
<li>Adobe Kuler's <a href="http://kuler.adobe.com/#create/fromacolor">Create > From a Color mode</a> &mdash; try with different "select a rule" modes
</ul>