You can also use them to purchase other gift cards, but it will depend on the store. (dannydealguru.com)
Home Depot gift cards are not the only ones available, however, You can find other gift cards on the Citi ThankYou reward program site as well. (upgradedpoints.com)
They also have $ 200 Visa gift cards and lots of other gift cards too. (doctorofcredit.com)