I don't know if it's still the case, but links with a 0 font size used to penalize you with search engines. Probably not a concern but just fyi.
Hunter Library, Western Carolina Univesity
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From: Ken Irwin <[log in to unmask]>
Sent: Thursday, January 07, 2010 11:56 PM
To: [log in to unmask] <[log in to unmask]>
Subject: Re: [CODE4LIB] image maps + lightbox/thickbox/ibox/etc -- SOLVED
Sometimes the answer is "quit working, go home, and ask your sweetie".
My partner is a genius and had a very straightforward solution: get rid of the imagemap and replace it with some absolutely-positioned links that use regular anchor tags. Not only does this solve the problem in a lightbox-friendly way, it also improves accessibility -- the links are now text with a font-size of zero: usable for a screen-reader and invisible to others.
Simple demo here: http://www6.wittenberg.edu/lib/testbed/imagemap/
Tomorrow perhaps I'll write a little script to convert my image maps to absolutely positioned elements for the more complex real-life image maps.