locationchanger (20KB download link, MacOSXHints mirror) is designed to automatically reconfigure many programs and resources according to IP address, wireless network ID, or dial-up connections. Currently it's capable of automatically modifying the following:
- NFS automounts
- Privoxy settings
- host file settings
- default printer
- Mail server and account
- iChat status
- Location setting in Network Preferences
[robg adds: I haven't tested this one, but I know that location management is a topic of interest, so here it is. Please read the entire Read Me file before proceeding, as there are important notes in there. There's also a simple uninstall script, in case you change your mind.]

