Adding games not on the list?

I don't think so. We try to keep to Steam games here on Steam gifts.

I guess another reason is is because Steam is an easy way to send gifts over. Giving away accounts or keys that require you to pirate it,etc. is just going to cause problems.

i still have an indie bundle from christmas i gifted someone and they never redeemed, but i checked and didn't see it on the list. what to do :(

I see no problem with this as long as it was locked to private giveaways only.