Sometimes you simply want to keep a post in your feed for a while. Sticky posts allows you to do that. Click on the 'stick' link on a post, and that post will remain on the top of your feed until you 'unstick' it.
That's it.
You can thank forwardslash for this one. It's one of those ideas that seemed so useful that we had to implement it straight away.
As always feedback is much appreciated.