Hi,
With FW 1.21 (what I have) DNS RELAY DOES have to be enabled for website filtering to work....Whitelisting or Blacklisting was one of the first things that was added to the FW after version ummm 1.03 or so due to our effective complaining a couple years back (or so); DLink DID listen to us on that issue. I was one of the chief whiners about it so I speak with "authoritae"
DO keep in mind that simply using a program like AOL bypasses website filtering entirely because it acts as a defacto proxy that doesn't register at all with the router's filtering routines.
If you are running a cafe' with internet access...the DIR-655 may not be the best choice if you are trying to keep it locked down tight.
You might also want to look at using one of the popular DNS services that does website blocking for you....I have read about them, but I use OpenDNS myself at home to assist. These DNS services are "supposed" to scrub DNS lists for "family friendly" purposes or whatever choices you define....