Feedburner offers a feed-splicing service, and a lot of people use this to splice their del.icio.us links into their blog feed.
But I have decided this is annoying, and I find myself unsubscribing from feeds that have far more del.icio.us links than real posts. It is perfectly possible to subscribe to a person's del.icio.us links separately, if anyone wants.
I'd rather have just one interesting post every month. Surely the whole point of feeds is that you don't have to keep the channel busy in order to keep the channel open.
(The guilty parties include several industry analysts, as well as employees of certain very large software companies.)
At least Feedburner doesn't offer a Twitter splicer yet. I hope they never do.