Here are the terms of the Amazon $100 GC:
Terms and conditions:
Limit: one promotional certificate per customer. This offer is valid only from February 22, 2002, until 11:59 p.m. PST on March 11, 2002.
Prepaid phones and prepaid plans are not eligible.
You must activate a plan of $29.99 or higher.
Offer is void if you cancel service or return the phone within 30 days.
Any unused balance will be placed in the recipient's gift certificate account.
A purchase of cell phone accessories without a cell phone activation does not qualify for the offer.
This promotional certificate will expire at 11:59 p.m. PST on September 30, 2002.
Promotional certificates must be redeemed through our Web site,
http://www.amazon.com, toward the purchase of products listed in Amazon.com's online catalog and sold by Amazon.com.
Promotional certificates cannot be redeemed at Amazon.co.uk, Amazon.de, Amazon.fr, Amazon.co.jp, or any other Web site operated by Amazon.com, its affiliates, or third-party merchants accessible from our site (including, for example, our Health & Beauty store operated by drugstore.com). Promotional certificates are not valid for payment at Amazon Marketplace, or Amazon.com Auctions or zShops.
Promotional certificate cash value is one-tenth of one cent.
Promotional certificates are not for resale.
Promotional certificates cannot be applied to orders already placed with us.
You must pay for the balance with a credit card.