Some recent posts at the 37signals Product Blog:

New Basecamp Customer Video: NYSE TransactTools
TransactTools is the commercial technology arm of the New York Stock Exchange.

NYSE TransactTools video.

Previewing the revised Basecamp Dashboard
We’re always looking for ways to improve the organization of the information presented on this information-heavy screen.

Store your account/login info at Highrise
“Highrise is great for aggregating information about all the accounts I have for various web applications.”

Use Basecamp and FreshBooks to generate invoices and track time
FreshBooks is an online invoicing and time tracking service that recently annouced integration with Basecamp.

Writeboard and Writeroom = distraction-free writing with version control
You have no choice but to write something or get up and do something else. And you’ve got an easy way to collaborate, track changes, and revert to earlier versions.

Adding repeating events to the Backpack Calendar
We’ve always supported repeating events that were brought in via an iCalendar subscription, but now you can create your own repeating events.

Repeating events arrive.