OK, it seems like there is at least a little bit of interest in an easy-to-use build.
I'll give a try at building a recent image (with "reasonably working" wireless code). I'm going to propose using the following config, with everything built into the image rather than relying on modules, which should make it dead simple to install.
All right--here is a torrent for a turnkey OpenWRT .IMG file that you should be able to install using the manufacturer's interface for uploading firmware. This brings up both wireless radios, the LAN and WAN ports, and has fancy blinking lights.
Before you download this, please make sure that you would be comfortable using the TFTP unbrick method (mentioned in the WNDR3700 wiki page) to restore the manufacturer's firmware, in the event that this build does not work for you and/or you wish to go back.
http://linuxtracker.org/index.php?page= … 534c9bb4e5
This was built with the config I specified a few messages above, using trunk revision 19642. The only changes compared to the trunk should be:
1) it includes the LED patches mentioned from a few messages ago, and
2) the mac80211 scripts were tweaked slightly so that the wireless interface is brought up on first boot (rather than being disabled, as it is by default). The wireless radios will be configured for the USA regulatory domain, so if you happen to live in another country, you should quickly telnet into 192.168.1.1 and edit /etc/config/wireless, adjust the country settings for both radios, and then run "wifi" to restart the wireless interface.
Please let me know how this works, either way! (Thanks go to all of the people on the thread who are already seeding this image.)