You could just go to the regular search menu, select the forums you want, and choose the "Find Posts From -> Your Last Visit" dropdown option.
However if you wanted to simplify it, your hack idea would require nothing more than 1 new template (to just display the forum list), and modifying the search.php to rewrite the do=getnew action.
ok this is what i came up with so far... please dont laugh...lol
//open search.php
//what do i change here ??? i dunno... im not good with conditionals....
if ($_REQUEST['do'] == 'getnew' OR $_REQUEST['do'] == 'getdaily')
{
globalize($_REQUEST, array(
'forumid' => INT,
'days' => INT,
'exclude' => STR
));
// get date:
if ($_REQUEST['do'] == 'getnew' AND $bbuserinfo['lastvisit'] != 0)
{
// if action = getnew and last visit date is set
$datecut = $bbuserinfo['lastvisit'];
}
else
{
$_REQUEST['do'] = 'getdaily';
if ($days < 1)
{
$days = 1;
}
$datecut = TIMENOW - (24 * 60 * 60 * $days);
}
################################################
//new template "newpostsearch"
<td width="50%">
<fieldset class="fieldset" style="margin:0px">
<legend>$vbphrase[search_in_forums]</legend>
<div style="padding:$stylevar[formspacer]px">
<div>
<select style="width:100%" name="forumchoice[]" size="13" multiple="multiple">
<option value="0" $noforumselected>$vbphrase[search_all_open_forums]</option>
<option value="subscribed">$vbphrase[search_subscribed_forums]</option>
$searchforumbits
</select>
</div>
<div><label for="cb_childforums"><input type="checkbox" name="childforums" value="1" id="cb_childforums" $childforumschecked[1] />$vbphrase[also_search_in_child_forums]</label></div>
</div>
</fieldset>
</td>
</tr>
</table>
</div>
#################################################
// edit usercp shell
##### Find ####
<tr>
<td class="$navclass[profilepic]" nowrap="nowrap"><a class="smallfont" href="profile.php?$session[sessionurl]do=editprofilepic">$vbphrase[edit_profile_picture]</a></td>
</tr>
</if>
###### Below Add ############
//something to this effect
<if condition="$show['newsearchlink']">
<tr>
<td class="$navclass[newpost]" nowrap="nowrap"><a class="smallfont" href="search.php?$session[sessionurl]do=confignewpostsearch">$vbphrase[new_post_forum_search]</a></td>
</tr>
help!!!! am i close???
edit: o and ill probably need one new phrase for the edit new search options
lol .... one more edit: id probably need to add this to the end of the new template: this or something like it
<p align="center">
<select name="saveprefs">
<option value="1" selected="selected">$vbphrase[save_search_preferences]</option>
<option value="0">$vbphrase[clear_search_preferences]</option>
</select>
<input type="submit" class="button" name="doprefs" value="$vbphrase[go]" />
<input type="image" src="$vboptions[cleargifurl]" width="1" height="1" />
</p>