Communication. Old Dog, New Tricks: Mod a Linksys WRT54G-series Router. Take a plain, ordinary (read: boring, with limited functionality) $60 wireless router and supercharge it with cool features and lots more functionality, control, and diagnostics. There's much more under the hood of these devices than is accessible with the vendor's default firmware versions. Even the updates from the vendor's support website unlock only a fraction of the router's capabilities.
Third-party developers have made firmware upgrades available that unleash a lot more functionality. "What is this 'firmware' of which you speak? " you ask. Well, that router is really just a fancy pile of switches waiting to be told what to do; that's the hardware. Top 10: Top 10 Network Utilities - Lifehacker. My IP Address Lookup and IP Address Locator. Socket++ - Linuxhacker.