I work retail at a computer store and as such I get to win free codes I don't use from Microsoft ExpertZone. Here are some XBox live codes that probably are not usable on PC, and therefore aren't very useful to me.
P.S. This part only applies to retail sales people: I assume if you're in this thread, you might be interested in other giveaways, so if you work at an official vendor and are willing to sell out or skim through some trainings, you should be doing stuff like this. Intel's retail training site is where I win the big bucks like consoles and trips to Disney World. Microsoft Expertzone is alright, their old site gave me shirts, hats, bottles, and fanny packs. LG's training site needs work but I'm supposedly getting a fancy projector from there, too. HP's training app Sellpro is pretty random but I've won more starbucks gift cards than I can use. If you win codes you don't want, you should be posting them here, most people don't even try and there are prizes that go unclaimed every day.