Thanks for the offer but I'm actually after an used humblebundle.com gift url, rather than keys at any particular digital download service. I just recently discovered I could integrate all the various bundles into a single Humble Bundle account and I want to complete my collection.
Ah, alright. I'm not sure how used gift bundles will work, but I'm pretty sure they're tied to the email address they were bought at, unless I'm mistaken.
EDIT: Ah, nevermind. Seems gifts work differently, so long as the original recipient hasn't claimed it.