best way to see and switch-between wireless networks?

[BSD baby]

I just got my wireless connection working with a new PCMCIA card.

But I'm still naming the wireless network in my rc.conf file. (DHCP connection)

But as I go to join other wireless DHCP networks around the world, what's the best way to:

#1 - see what networks are available (and perhaps their strength?)
#2 - switch to that network without rebooting to do it from rc.conf?

If there's a tutorial about this kind of thing (besides /handbook/network-wireless.html) - please point me there.

Thanks!