We do active development on Zope and Plone, and have a number of Plone products:

• GrailTact - A contact database, with GMail etc. syncing planned
• MegamanicEdit - A tool to edit multiple Plone Archetypes-based objects at once
• PermissionComprehensible - A tool to view (and later edit) complicated permission settings.
• EasyUserAuthenticationPlugin - A tool to easily integrate Plone logins with for example IMAP backends
• PloneContentTemplates - A tool to make given portal content into content templates; useful for repetitive content.
• VariousDisplayWidgets - widgets to show Emails and URIs as clickable links.
• SimpleChat - A Zope or Plone product for user messaging.
  
• PloneboardComments - A Plone product which moves the default Plone commenting system to Ploneboard forums.
• RestrictedSize - a Plone product which restricts the size (number of characters) on input, using server-side and client side technology.
• ReverseFolderContents - a Plone product which enables reversing the folder contents
• Products.PatchPloneContent - a Plone product that provides some useful tools to manipulate plone (archetypes) content
  
• Products.PurgeMissingObjectInterfaces - A Zope product to clear old marker interface cruft

Pure Zope-products also worth mentioning:

• Spaceman - A tool to see which folders in Zope are taking up space
• Zope undo tool - A tool to undo transactions based on a given date. (Note, 1.0 works best).

And a Zope 3 product worth mentioning:

• Boring for Zope 3 - A demonstration on how to develop for Zope 3.

Some other things worth mentioning:

PloneboardRestrictedSize, a product which was developed to integrate RestrictedSize with Ploneboard 2.1.  It was intended to be a product, but time and cost constraints towards the customer that needed the integration forced a solution where only the .cpt and .py files from the product were put into the portal_skins/custom folder instead.  (It requires the installation of RestrictedSize as well).