The magic ink paper was on top of HN 2 years ago[1]. I remember bouncing off it the first half dozen times I ran across it on the blogosphere. Eventually I focused, and boy was it worth it:

http://worrydream.com/MagicInk

It's still my #1 paper of all time, for both exposition and presentation (layout, typography, figures), and the paper I have quoted most often on my linkblog (http://akkartik.name/search_results?q=bret+victor)

I wanted to submit this to the recent thread on the future of UI (http://news.ycombinator.com/item?id=1055194)

[1] http://news.ycombinator.com/item?id=8120. 19 points was a lot in those days.

Edit: searchyc tells me it was resubmitted 8 months ago with success (http://news.ycombinator.com/item?id=600799)