hi all!
regarding the method from jclayc (using link_notes field to save the expired date of link), i just add this code in line 65 of wp-includes/bookmark-template.php file :
before :
foreach ( (array) $bookmarks as $bookmark ) {
if ( !isset($bookmark->recently_updated) )
after :
foreach ( (array) $bookmarks as $bookmark ) {
// this is additional line :
if ($bookmark->link_notes<>'' && $bookmark->link_notes < date("Y-m-d")) continue;
if ( !isset($bookmark->recently_updated) )
in this case i used this date format : YYYY-MM-DD.
cmiiw.