Useful Modules?

I have tried to install only modules that I needed to meet the immediate designs I was trying to achieve.  In my travels, though, I thought these modules looked very interesting and worth checking out:

- Hovertips and Clicktips |  - uses JQuery (AJAX) to create nice pop-up or roll-down tips.  Really useful for displaying complex information or hiding stuff that's not used much (e.g., hide all comments current user has already seen.

- Panels |  - provides API and UI for creating sophisticated panelled layouts.  With related "mini-panel" modules to add AJAX tabbed panels and carousel panels Mini Panels demo | Wim Leers

- Node Queue | - allows you to display items from a "queue" that automatically drops last item when a new one is added.  Can be used manually for creating "top 5" type lists, or integrated with actions module to automate.

- module_builder - I install this locally to make custom module development easier.  It simple creates a template for a new module based on a few settings.  Only useful for developing a new custom module from scratch.

- form_inspect - a companion for the devel module, this is useful if you are working with forms (say implementing a hook_form_alter), and want an easy way to see view the form data structure.

- chipin - for collecting money for a cause  ** NOT AVAILABLE in 5.0 YET **

- nodewords - meta tag (description, keywords) for each page.

- rsvp - enables rsvp for events (probably won't work with the CCK event types I defined :-(   Perhaps re-develop for CCK date field?)

- volunteer_timeslots - for organising events where volunteers sign up for a timeslot - ditto!

- spam - spam blocking tools. 

- taxonomy_access - access control for users based on taxonomy categories.

-taxonomy_role - access control to taxonomy field on node-edit forms.  Useful to allow admin to place "hidden" taxonomy term in a node, probably for organisational purposes.

- cck_role - same thing for a CCK field.  Could be handy.

- Notifications - a potential replacement / upgrade for Notify and/or Subscriptions?

- Custom Breadcrumb - format breadcrumbs for custom views.