Wi-Fi security using linux-based router

[vodhner at cox.net]

About a month ago I bought a Linux-based Linksys wireless router,
WRT54GL v1.  By the way, as I approached the Linksys shelf at
Fry's (Northwest Phoenix) it was the first box I came to ... didn't
have to search.

Are there any interesting things I can install on it, to improve the
security of my wireless network?

I found one link right away, which I haven't looked at yet:

http://www.sns.ias.edu/~jns/wp/2006/03/24/iptables-on-a-linksys-cisco-wrt54gl-broadband-router-howto/

I'm just fishing for any pointers or recommendations that will give
me a boost.  I'm specifically interested in controlling what wireless
connections can see, and maybe limiting access to specific PCs.

Thanks,

Vic