Probably the best web-based firewall rules editor that I have seen is the one that comes with NetMAX (
www.netmax.com). It is very flexible and very powerful.
The caveat there is that you can also do horrendous things to your firewall with that power and flexibility, so you *need to know what you are doing*.
I do not believe that the vast majority of SME users out there know, or indeed want to know, exactly how their firewall works or how the rules should be crafted for maximum security. It should be left as white-man magic.
Having said that, the _option_ of crafting the rules with the specific granularity that the NetMAX model provides is very tempting. Having it as a separate server-manager contrib option, which would have a biiig warning at the top of it, would be good.
Sean