Our latest work involves development of a subscription system using Wordpress on the popular financial blog, Footnoted.org. The requirements of the system were as follows:

A subscriber registration and payment processing interface
System tracking of subscription expiration dates
Download management allowing the administrator to easily upload files as well as restricting file downloads to paying subscribers only
An email [...]

Recently, a client asked if I could create some ad spaces on his Wordpress blog that he could administer himself. The requirements:

ad spaces of differing sizes
ad spaces in multiple locations on the site
a simple administration interface with the ability to input ads with HTML code or to upload an image with a link