Dan’s Deals flags free wifi codes for United, US Airways, and American.
When flying AA use code: HPAA
When flying United use code: HPUNITED
When flying USeless Airways use code: HPUSAIRWAYS
Expiration of the codes is unknown.
Now, there isn’t a whole lot of wifi going on at US Airways and United, but it’s reasonably widespread at American.
And of course, with Airtran, Delta, and Virgin America wifi is free from November 20 through January 2 anyway.
(HT: Frugal Travel Guy.)