DD-WRT is fantastic for getting business class features without the business class hardware costs (if you can get by with number of devices vs SOHO quality hardware).
MAC filtering I'd just make one point about though. This shouldn't be relied on as a form of security. It's very easy to change what MAC address one's device apears to connect from and the list of valid MAC addresses only takes a little longer than finding a "hidden" SSID (ie. secounds). You still need that good strong WPA2 passphrase providing a real security mechanism.
Now, MAC filtering is good for reducing load on the router. I don't want my device paying attention to every wireless broadcast within range. It should pay attention only to devices that apear to be relevant. Thus, allow only MAC addresses in the filter list and ignore all the rest.
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