Are you looking to enhance the security provided by your WL-500G (Deluxe or Premium)?  Then check out the PacketProtector firmware project.

Here's what you get-

* a stateful firewall (iptables)
* WPA/WPA2 Enterprise wireless (802.1X and PEAP with FreeRADIUS)
* intrusion prevention (Snort-inline)
* intrusion detection (Snort)
* remote access VPN (OpenVPN)
* content filtering/parental controls (Dansguardian)
* web antivirus (DG + ClamAV)
* a local certificate authority (OpenSSL)
* secure management interfaces (SSH and HTTPS)
* advanced firewall scripts for blocking IM and P2P apps
* IP spoofing prevention (Linux rp_filter)
* basic protocol anomaly detection (ipt_unclean)

Thanks!
Charlie