The one I use the most, by far, is "Plain Text Paste," which I use almost every time I paste anything (I use the hotkey CMD-SHIFT-V). It's here: http://cachefly.alfredapp.com/beta/Plain%20Text%20Paste.alfr...
The only other workflows I use regularly are hotkeys to open websites I visit regularly, like our own website and our WordPress log-in control panel.
I'd too would love to hear which workflows other HN readers use a lot.