I use KiWiFiManager for configuring my wireless connection. Has the ability to scan for connections and load different configuration files depending on which network you're connecting into, but I've never actually used it switch between networks. Has a problem dealing with WEP encryption, but it might just be my card, so I have a script to setup the encryption separately, but other than that it works fine. Haven't tried any others to be honest, so can't really draw comparisons with out tools, but I'd give it a thumbs up. Should be included with a default KDE install that includes Internet applications, or available from
http://www.kde-apps.org
