Is there any way to enter those crazy 25-character alphanumeric Xbox Live redeem codes online instead of via Xbox 360 controller?
I have my XBL account linked with a Microsoft Passport account, if that helps....
Yes, you can login to the Xbox Marketplace and redeem the code there. Click the "Redeem Code" link under "My Account."
https://live.xbox.com/RedeemToken seems to be the current place to go.