I'm too lazy to package this as a mod file, but I thought I'd share it in case others are interested.
On my boards I have users from around the world who like to schedule things to do in a game. The calendar was part of the solution, but still left some room for confusion regarding timezones.
I'd added a new board tag to my board called
time which allows users to enter a time in their local time, to schedule events, and when users read the message it gets converted to that user's local time.
If you want a little better description of it, or to play around with it, you can here:
Time Thread. Note that if you want to see what it actually looks like you'll need to make a member account since it cannot convert a guest to any local time format. I added a picture of what it does, since creating an account is probably a pain just to see it. If you want to play around with it, you'll still need an account, but here is what it does basically:

This should probably be considered BETA as well. I have it up and running and it appears to be working right, but until it's had a pretty heavy usage I won't know for sure....
To add the tag:
In
Subs.php find the function
doparsecodesmilies. At the end of this function, just before the
return $message; add the following:
$nUserOffset = (isset($settings[18]) ? $settings[18] : 0);
while (preg_match("/\[time\](.+?)\[\/time\]/i", $message, $matches))
{
$searchfor = $matches[1];
if ($ID_MEMBER != -1)
{
// Only members get a time translation.
$nTime = strtotime($searchfor) + (($timeoffset+$nUserOffset)*3600);
$sTimeResult = strftime("%a, %b %d at %I:%M %p (Local Time)",$nTime);
$message = str_replace("[time]".$searchfor."[/time]",$sTimeResult,$message);
}
else
$message = str_replace("[time]".$searchfor."[/time]",$searchfor,$message);
}
In that same function, at the very top, right under the existing
global statment, add this line:
global $timeoffset,$settings,$ID_MEMBER;
That's all that is needed for the tag to work. If you want to add the
time tag to the posting form, you can do the following....
Here is an image for the button, stick it in your images directory:

Load up
Post.php and search for
javascript:bold(). That's the start of a ridiculously huge line. Add to the end of that line, but right before the
<br> the following:
<a href="javascript:timetag()"><img src="$imagesdir/time.gif" align=bottom width=23 height=22 alt="Time" border=0></a>
Now load up
ubbc.js and add to the end of the file:
function timetag() {
AddTxt="[time][/time]";
AddText(AddTxt);
}
That's it.