37 Signals Products
Basecamp
Basecamp allows you to create projects, assign to-do items, collaborate on text documents, have a message board you can share with your clients (similar to a blog with comments)
Highrise
Highrise tracks contact with your clients. See who talked to which client, when they spoke, and what it was about. Schedule reminders delivered via email or SMS for follow up contact.
Backpack
Backpack offers a shared group calendar, intranet webpages, and file sharing within your group.