I like this suggestion for pinned tweets from Alex Pankratov:

The idea is to reserve the top part of my tweet stream for tweets that are promoted, or pinned, by their posters. This way if I go on a vacation and a vendor ships an update, I will still see the news when I get back:

Once a pinned tweet is shown to me, it starts dropping down in my timeline as usual. Think of it as a delayed, on-demand tweet delivery.

I’d propose a variation of this idea though — perhaps pinned tweets could be generated from the tweets that people I follow are favouriting and retweeting a lot. Many people use favourites to bookmark tweets they want to follow up on, so Twitter could encourage this behaviour, perhaps by changing favourites into pins.

Now, following along with the example above, if enough people who follow @Sparrow pin that tweet, it’ll appear at the top of my timeline next time I check in, along with the best of the other stuff that I’ve been missing out on. And like the favourites, these pinned tweets will continue to be available for my reference at twitter.com/pinned or somewhere.

Downsides

• Individual tweets are already pretty cluttered with metadata. This would introduce yet more complexity.
• In this variation of the pinned tweet ideas, paid-for promotions may be less welcome as they would be seen to be intruding on a user-generated feature.