Here are some more promo codes I've run across:
53096 - Adds 30 days to your expiration date for any card, so your lowst cost per month can be $4.33 or so with a $13 40-minute card off of eBay (but it would probably be wiser just to get the 40 extra minute promo)
52989 - Doubles the minutes on 200 and 400 minute cards (usuable only once per phone); if you get a 400 card off of eBay for $65 (they're there) the minutes cost an astoundingly low 8.125 cents per! If you get a 200-minute card off of This Site for $38, your minutes will be 9.5 cents a minute! Not bad for less than $50 or less than $75 in airtime investments (T-Mobile $100 cards can be seen sometimes for $80, making for 8 cents a minute, but this is a pretty large cash layout for the price).
59585 - Adds 200 minutes to a 300 minute Double Minute card. On eBay these go for as low as $115, so along with doubling your minutes purchased on cards for one year (but I don't think other sweet promos apply :( ) you also get 500 minutes which makes each minute cost 23 cents. Not bad for a multipurpose 1-year card on a normally atrociously-overpriced carrier.
There are also a few databases of Tracfone promo codes. I got the first code straight from the database, and the other two are also in there. I got them from the first database; the second one lists the same codes you would find in your Tracfone's promotional booklet. The address is: