예로
썸네일 폴더가 thumb 이고 해당 파일이 wr_id 값이라고 했을때입니다..

이미지 아이디 값을 ch_img 로 주었습니다.

<img id=ch_img src="zz.gif">
<script language=Javascript>
function ch_img(idx)
{
document.getElementById("ch_img").src="<?=$g4[path]?>/data/file/<?=$bo_table?>/thumb/"+idx;
}
</script>

해당 서브젝트 부분($list[$i][subject]) 의 앵커태그에 onmouseover=ch_img("<?=$list[wr_id]?>");

추가해주시면 될거같은데.....제가 테스트 해보진 않아서 -_-;;

언젠가 작업했던 거네요. (http://www.selca.co.kr/)

1. 최신글스킨 : 파일을 만들어서 latest 폴더에 업로드

<script type="text/javascript">COUNT["<?php echo $bo_table; ?>"] = <?php echo count($list); ?>;</script>
<table width="334" border="0" cellspacing="0" cellpadding="0" align="center">
<tr height="26">
<td><img src="<?php echo $g4['path']; ?>/img/i_bullet.jpg" align="absmiddle"> <strong><?php echo $board['bo_subject']; ?></strong></td>
<td align="right" class="small" style="padding:7px 0 0 0;"><a href="<?php echo $g4['bbs_path']; ?>/board.php?bo_table=<?php echo $bo_table; ?>" onfocus="this.blur();" style="color:#969696;">더보기</a></td>
</tr>
<tr><td background="<?php echo $g4['path']; ?>/img/g_dot.jpg" colspan="2"></td></tr>
<tr><td height="10" colspan="2"></td></tr>
<tr><td height="104" colspan="2">
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td width="98" style="border:3px solid #EBEBEB;">
<?php for($i = 0; $i < count($list); $i++){ ?>
<div id="<?php echo "{$bo_table}_{$i}"; ?>" style="<?php if($i == 0) echo 'display:block;'; else echo 'display:none;'; ?>"><a href="<?php echo $list[$i]['href']; ?>" onfocus="this.blur();"><?php echo THUMB_NAIL("{$list[$i]['file']['0']['path']}/{$list[$i]['file']['0']['file']}", "{$g4['path']}/data/thumb/{$list[$i]['file']['0']['file']}.thumb", 98, 98); ?></a></div>
<?php } ?>
</td>
<td width="12"></td>
<td width="" valign="top" style="padding:3px 0 0 0;">
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<?php for($i = 0; $i < count($list); $i++){ ?>
<tr><td height="20"><img src="<?php echo $g4['path']; ?>/img/i_bullet.jpg" align="absmiddle"> <a href="<?php echo $list[$i]['href']; ?>" onmouseover="layer('<?php echo $bo_table; ?>', '<?php echo $i; ?>');" onfocus="this.blur();" style="color:#222222;"><?php echo str_replace('…', '..', $list[$i]['subject']) . $list[$i]['comment_cnt']; ?></a></td></tr>
<?php } ?>
</table>
</td>
</tr>
</table>
</td></tr>
</table>

스크립트파일 : common.js에 추가
var COUNT = new Array();
function layer(id, no)
{
for(var i = 0; i < COUNT[id]; i++)
{
document.getElementById(id + "_" + i).style.display = "none";
}
document.getElementById(id + "_" + no).style.display = "block";
return;
}

썸네일함수 : common.lib에 추가
function THUMB_NAIL($exist, $creat, $width, $height)
{
global $g4;
if(file_exists($exist) == true && in_array(strtolower(array_pop(explode('.', $exist))), array('gif', 'jpg', 'jpeg', 'png')) == true)
{
if(file_exists($creat) == false)
{
list($img['width'], $img['height'], $img['type']) = getimagesize($exist);
switch($img['type'])
{
case '1' :

$src['image'] = imagecreatefromgif($exist);
$dst['image'] = imagecreate($width, $height);
break;

case '2' :

$src['image'] = imagecreatefromjpeg($exist);
$dst['image'] = imagecreatetruecolor($width, $height);
break;

case '3' :

$src['image'] = imagecreatefrompng($exist);
$dst['image'] = imagecreatetruecolor($width, $height);
break;
}
$dst['color'] = imagecolorallocate($dst['image'], 255, 255, 255);
imagefilledrectangle($dst['image'], 0, 0, $width, $height, $dst['color']);
imagecopyresampled($dst['image'], $src['image'], 0, 0, 0, 0, $width, $height, $img['width'], $img['height']);
switch($img['type'])
{
case '1' :

imagegif($dst['image'], $creat);
break;

case '2' :

imagejpeg($dst['image'], $creat, 100);
break;

case '3' :

imagepng($dst['image'], $creat, 100);
break;
}
imagedestroy($src['image']);
imagedestroy($dst['image']);
}
$return = "<img src=\"{$creat}\">";
}
else
{
$return = "<img src=\"{$g4['path']}/img/p_null.jpg\">";
}
return $return;
}