Pocket

Pocket is a save-for-later tool — when you come across an article worth reading or referencing while you're not ready to deal with it, you save it to Pocket and it's there when you have time, stripped of ads and formatted for reading.

For a newsletter, it doubles as a lightweight content pipeline: a running list of links worth mentioning that builds up over the week, so that when it's time to actually write an issue, you're pulling from a curated stack of saved material instead of starting from a blank page and trying to remember what you'd seen.