Many html editors (esp. those that u have to pay for) such as dreamweaver, etc. have built in image map creation facility. If u want free software, check this link
*www.download.com/3120-2001_4-0-1-0...nk=&gfiletype=&os=&li=49&dlsize=&ca=&x=11&y=6
It is list of couple of image mapping software of free license available at download.com
Also check this link *www.fegi.ru/geohtml/
Hope this helps,
Arun