New guy here. I may have a solution for you. I just (as in today) took a router that was compatible with tomato-usb firmware and had a USB port and made a poor mans weatherhub. Parts needed:
1 wireless router with a usb port that is supported by dd-wrt, tomatousb or openwrt firmware
1 usb hub (not needed if the router has 2 usb ports) - unpowered hub will work fine
1 usb flash drive, 1GB is more than enough
Basically flash tomato-usb (or openwrt or dd-wrt, whatever the router you have supports), connect the hub to the router and plug in the flash drive, install optware on the flash drive (instructions here
http://www.dd-wrt.com/wiki/index.php/Optware,_the_Right_Way ), then grab pywws from here
http://code.google.com/p/pywws/ and install it on the flash drive.
Once you have everything configured, you can have the router send updates to weather underground, pws etc and even have it ftp them to another computer in your home. If you wanted to get really fancy I think it's possible with the scripts in pywws to build a mini webserver on the router as well.
I'm still waiting for weather underground to start showing my station data though. It does say it's active, but no data yet...but it's only been 2 hours and the station has never been online before. If it works and anyone's interested I'll put together a more detailed how-to.
BTW, total cost including the router $35 bucks
EDIT: Just checked and it's reporting to weather underground. Let me know if there's interest in a detailed how-to.