Custom Modules?

Almost everything I ever thought of has been done in Drupal by someone else - it's a beautiful thing.  But there have been a few things I've imagined would be really useful that I couldn't find anywhere...
I'd consider writing these myself one day, if time ever permits...

Expiry Date

This module would define a new CCK date type (using Date API) to define an expiry date for a node.  The node owner would get an e-mail reminding them that their node was about to expire, and if no action was taken, the node would simply be removed.   This would be very handy for announcements and to create a CCK classified ads module.  Code could largely be ripped from ed_classified module.

Replace Title

This module would look for an image in a specific directory with a name "similar" to the node title.  If a suitable image is found, then replace the node title with the image.  Use hook_node_?
DONE: But code in template.php - need to move it to a custom module.

Publishing Options Access

This small module uses a hook_form_alter to create per-role access rights to elements of the Publishing Options fieldset on the node-edit form.  This would allow admin to grant rights to user-roles to, for example, promote to front page.
I have already made a good start on this module and will look to contributing it.

Summary Views Plugins

A View with an argument creates a "summary view" when the argument is missing.  The default summary view is simply a list of potentail argument values, linked to their repsepective view "pages".   I could only find one example of a customized summary view (Example: How to Display a Summary View as a Mock Menu | drupal.org ).  I used this to create the "pop-open" menus when browsing the photo gallery, for example. 

I heard a rumour that Views Theming is going to get MUCH easier in Drupal 6, so this may be a wait-and-see.

But there are some other summary views I'd find a great use for:

• Image Gallery - the photo albums and galleries on lasqueti.ca are built with views, using user id, and taxonomy term, respectively, as arguments.  The "summary view" is custom coded in the phptemplate file of the lasqueti theme.  It would be nice to turn this into a real view plugin that shows the individual gallery views as a Bonus Grid.
  DONE: but currently coded in template.php - need to move to a custom module
• List All - it would be nice if the summary view could simply list all of the nodes, with a pager, in some order.  This could be as title links only, or as teasers, or, preferably, customisable.   To make this work flexibly, Views would have to support a different view-type selector for the summary view.
  TRY: Setting the argument option to List All in the View - probably does this?
• Nodes-by-Argument summary - would show all node titles, with links, organized by the argument values (e.g., by the taxonomy tree, for example.)  I have written a preliminary version of this module named nodes-by-category.  Perhaps directory plugin?  or nodes-by-category summary?
  Started: custom Nodes-by-Category views plugin.
  TRY: Views Group-by to group nodes by term in the summary?
• Single-Node- for views that return just a single node (e.g., random image block), the table or list markup is superfulous and requires special styling to make it invisible.  This view simply outputs one node, with no layout formatting.
  DONE: custom views plugin written.