You don't always need php (POTD Script)

[raymor]

If you're rotating the pic each day a really simple and fast way is to
use the date variables in rewrite. This example is from a guy who wanted
7 pics, so they would repeat each week. You can change the variable
to rotate through 31 pics, one for each day of the month, or 366 pics,
one for each day of the year. The HTML code:

<a href="potd.jpg"><img src="tn_potd.jpg></a>

The .htaccess:
RewriteRule ^tn_potd.jpg $ tn_%{TIME_WDAY}.jpg
RewriteRule ^potd.jpg $ %{TIME_WDAY}.jpg

SSI can also be used similarly, by echoing the proper portion of the current
date or time as part of the file name.