I've just migrated hosts for my website and managed to spam at least one aggregator in the process. (I think this is because git does not preserve timestamp metadata for blobs but I haven't investigated properly yet). Apologies to those affected. Luckily, I have my feed configured to only show the most recent 5 items, so the impact was quite small.
Asides from feeds, I think blog web pages that display an enormous number of posts on the front page (or inside category pages) are demonstrating some pretty bad usability. I thought that Jakob Nielsen may have included this in his Weblog Usability: The Top Ten Design Mistakes, but he didn't. Thomas Watson writes
Jonathan Boutelle describes an interesting compromise which he calls the "Mullet style" - a short list of full posts followed by a list of older posts, containing only their titles and date.