I made a script that takes the top 5 stories from Hacker News and feeds them to Twitter, so you can get breaking stories directly to your Twitter stream
It updates every hour so it should show new stories pretty regularly, I made this for myself but I thought that other people on here would fine it useful too
Hourly is good. Any more frequent and it might be annoying ;)
I made a very similar bot for del.icio.us popular too, if anyone's interested: