There are patches we can start creating and applying to core Drupal 6 aggregator today. Let's start getting them in one by in. Please flesh out requirements and notes. Link to related issues in queue. Feel free to move these items around or add extra comments. Would be great to see people pick these up and review all the others to see if we can get some great improvements in for 6 (and some are bugs that might be applied to 5.x).
To Do
Make creation of block per feed optional
* Been through a couple of reviews, needs testing and comments
* so many blocks "spam" the blocks page -- #43245
Add paging to Admin > Content > Aggregator Page
* this is simple and should just get done
* what about alpha paging? not in core yet, should get handled by contrib module (and likely with feeds as nodes)
Allow for sorting of "Sources" in the admin page
* this is highly related to paging -- being able to sort the table by the various fields
* Issues: #119690
Swap out Categories and replace with Taxonomy
* this is a bit more of a major change, and would mean a term id -- feed id join table
* opens the way to lots of other stuff (like, try doing term id -- user id at the same time; lots of talk of making taxonomy apply to more things)
Per-feed input filters
* right now, the tag filter applies to everything
* Issues: #89191
Troubleshoot compatibility of core parser
* the core parser has issues with some feeds; need to find out what those are
* Issues #127224 - various Wordpress / MSN Live (use #127224 as the main thread to report broken feeds), #124895 - Blogspot / Atom feeds
Fix PHP notices
* this should be easy
* patched -- ready for review
* Issues #132369
Get OPML Import in
* basically just need to keep re-rolling that patch
* Issues #16282
The return of "blog this"
* for aggregator items all over the place
* patched -- ready for review
* Issues #130732
Entity / tag stripping of feed titles
* Been around a while, and needs fixing cleanly
* Descriptions are being filtered with aggregator_filter_xss & titles were using check_plain. I've made titles match the description filtering. Does that seem like a clean enough solution for everyone involved?
* patched -- ready for review
* Issues #61456
Code style clean up
* seems obvious to just get this done
* Issues #108716