http://packages.ubuntu.com/
The Ubuntu package list. One can find .debs to download here.
http://www.fastspring.com/
Sell hosted content online. Two simple pricing structures 5.9% plus 95c per transaction or 8.9% with a 75c per transaction minimum. Highly customised order pages.
https://launchpad.net/ubuntu/+archivemirrors
Official list of Ubuntu mirrors including very useful information on how up to date they are and their available bandwidth.
https://www.payloadz.com/
Simple site to sell downloadable content. Integrates with a few payment gateways, PayPal, google checkout, amazon payments, and probably others. Free up to $50 a month or 5% plus 49c (5c < $2) per transaction, in addition to any checkout fees I assume.
