When you get to
http://www.dmoz.org/Society/People/Personal_Homepages/ you will see a line of letters across the top of the page (A-Z). Select the letter that corresponds to the first letter of the title of your web page. Once you select the letter - for example D for Dahlia - the suggest URL link will reappear.
The ability to suggest URLs is turned off in categories that require suggestions to be made to subcategories.