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.
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.
The commercial arm of a2billing, offering installation, support, and hosting.
a2billing is built on top of Asterisk and handles all kinds of billing requirements. Prepaid calling cards, post-paid, CLI authenticated, etc, etc. Very powerful. Commercial support available.
Expense reporting, time tracking and invoicing system. Starts from $12/mth for 1 user. $40/mth for 2-5 users. Pricey, but looks solid. Includes twitter based SMS/IM integration (neat). Feels quite ajaxy, nice design. Hat tip Jamie Cockburn.
Intervals is an online time tracking / invoicing system like FreshBooks / CashBoard. The web site seems dull. SSL is only available on $100/mth+ packages. $20/mth covers up to 10 projects, 500Mb, unlimited users.
Fire and Forget Expense Tracking. Fire in your expenses via twitter / im / email / sms / voice / etc. Then slap them together into expenses claims and send them automatically. I think Henk recommended it. Looks good, very ajaxy.
Online time tracking and invoicing tool like FreshBooks. Paid accounts from $12/mth, 7 projects, unlimited invoices, unbranded, online payments, pdf invoices. Looks good. Multi-currency support.
Blinksale is an online invoicing service, similar to FreshBooks, but with less functionality. Free for 3 invoices / month, $12/mth for 50, $24 for 250 including PDF invoicing, $49 for 1'500 invoices. Oozes ajax / rails / design. Integrates with PayPal.