A CSS based 3 Level Drop Down for Typo 3
Well... it's mostly CSS based when it comes to positioning of the elements. Ofcourse there is a little bit of JS needed to make the magic happen. I decided to use JS for both MS and Mozilla based browsers for the simple fact that I can keep the CSS the same between both browsers. It's only tested on FF 1.5 and IE 6 let me know if you works for you. I created this version so you all know how to make a thing like this in TYPO3.
Btw... YACBDDM stands for Yet Another CSS based drop down menu (for TYPO3)
A general structure for such a menu is like this: (taken from 
http://www.alistapart.com/)
<ul>
<li><a href="#">Home</a></li>
<li><a href="#">About</a>
<ul>
<li><a href="#">History</a></li>
<li><a href="#">Team</a></li>
<li><a href="#">Offices</a></li>
</ul>
</li>
<li><a href="#">Contact Us</a>
<ul>
<li><a href="#">United Kingdom</a></li>
<li><a href="#">France</a></li>
<li><a href="#">USA</a></li>
<li><a href="#">Australia</a></li>
</ul>
</li>
</ul>
The Typoscript for a menu like the above is straight forware. Simple un-ordered lists into each other. Make sure that the UL tag comes directly after the tag and not in it's own list element.
yacbddm = COA
yacbddm.10 = HMENU
yacbddm.10.1 = TMENU
yacbddm.10.1 {
noBlur = 1
expAll = 1
wrap = <ul id="yacbddm" class="topmenul1"> | </ul>
NO.wrapItemAndSub = <li> | </li>
NO.ATagParams = class="firstlevellink"
IFSUB=1
IFSUB {
wrapItemAndSub = <li> | </li>
ATagParams = class="firstlevellink topmenul1-ifsub"
}
}
# First dropdown Menu configuration
yacbddm.10.2 = TMENU
yacbddm.10.2 {
noBlur = 1
expAll = 1
wrap = <ul class="topmenul2"> | </ul>
NO.wrapItemAndSub = <li> | </li>
IFSUB=1
IFSUB {
wrapItemAndSub = <li> | </li>
ATagParams = class="topmenul2-ifsub"
}
}
# Second dropdown is the same is first drop down
yacbddm.10.3 < yacbddm.10.2
yacbddm.10.3.wrap = <ul class="topmenul3"> | </ul>
# Third dropdown is the same is first drop down
yacbddm.10.4 < yacbddm.10.2
yacbddm.10.4.wrap = <ul class="topmenul4"> | </ul>
yacbddm.20 = TEXT
yacbddm.20.value (
<script src="fileadmin/templates/scripts/yacbddm.js" type="text/javascript"></script>
<script type="text/javascript">/*activateMenu('yacbddm')*/</script>
)
Documentation for 
CSS and javascript (both downloadeable wil follow).
Will finnish this tomorrow