I'd like to see the last 100 or so recent posts at once, rather than four-per-page.

Robert,
That is the way we would like to see it too as it is easier to scroll down than go to a different page, and I think we have done that.
If you are on the main gallery page and click on the "recent uploads", you will see all the new uploads in a long page.
If you are in a certain category, let's say birds, for instance, you will see the new uploads in birds. Let me know if it works for you the same way it does for me,
Thanks

Yes that works well. The "Forum" button on top takes you to a page which still only shows 4 posts at once though.