You can use invisible Technorati tags when tagging your posts, although Technorati frown on it (sorry, I didn't manage to transfer the original Haloscan comment by Kevin Marks before it got deleted after 4 months).
But to generate invisible tags easily, as requested by Aiuto, the simplest way is probably to use the usual bookmarklet or (if you have Firefox) Greasemonkey script - see this post. Then (suggestion courtesy of my Magical Sheep pardner Truckspy), you make the tags invisible through CSS by adding this to your blog template, between the <style type="text/css"> and the </style> tags in your head section.
That ought to work and shouldn't stop Technorati from picking up your tags, assuming (assuming!) their bots read the source rather than the displayed page, but if anyone has problems do say. And remember Technorati (and possibly Google too) don't like invisible tags so they may well do something to stop invisible tags being indexed, so use 'em at your own risk! (I find it best to have my tags visible, but tiny, like in my posts).
Technorati Tags: Technorati, Technorati tags, invisible Technorati tags, tags, tag, tagging, invisible tags, Improbulus, A Consuming Experience, Consuming Experience