I won a free wireless router at the Irish Blog Awards a few weeks ago. Its a Linksys WRT54GL, but came with FON software pre-installed. I have nothing against FON and their aims but I found the software hard to use and configure. So this week I reflashed the router with the original Linksys software.
This is a straightforward process. First connect the router to a PC via a bit of ethernet cable. Now boot the router and login via http://192.168.0.1 (it might have been http://192.168.1.1). Go to the system table and look for the upgrade dialog. This upgrade dialog allows you to select a local file to upgrade the router. You can download the Linksys firmware from the linksys website. So download that file and feed it to the upgrade dialog.
The upgrade screen will print out some messages about unpacking the file and once it prints done you have completed the upload. The final step is to press the button on the front of the router to reboot the system. The light behind this button will flash furiously for a few minutes and when it settles down you have a fully configured and working original Linksys router.
Full docs are again available on the Linksys page.