If it's starting to get a bit ridiculous, then you might be interested in using a Mega dropdown menu. That link has screenshots to sites who are using them.
Usually if you have soooo many links in a category, possibly they can be further grouped. Making the main li's contain a div with many separate lists inside is a popular solution:
<a href="f00dz">Category: f00dz</a>
<li><a href="#">Tom poes</a></li>
<h3>Food Co.'s specialty sour:</h3>
The anchor sitting there between blocks may trigger a bug in IE. If it does, wrap a p or something around it.
You can add in header elements, borders, and other things if that makes searching clearer for the user.
One thing you have to be very careful with is, because these things get so big, they might be larger than the user's screen. Keep them as small as you can get away with: unless the user has a scroll-wheel, they won't be able to scroll the page if the page-height grows only when they hover.