1. CTRL+click
2. Middle-click
3. Right-click link -> Open in new tab.
One of them should (hopefully) work if you are using a browser that supports tabbed windows.
;)
EDIT: Almost forgot this one: If you are browsing on your mobile device, long-press -> "open in new tab" or "open in background tab" should (ideally) work.
IMHO, I think he chose reveal.js because it was so highly regarded on HN just a few days ago. I don't think he would've expect that people would comment on that rather than his actual efforts, a.k.a. the bookmark storage and search.
When someone makes a website, they always base their designs around certain assumptions; his was to assume that people usually open new links in tabs. (I do, too.) Over time and after feedback is when these decisions are either vindicated or proven wrong.
I apologize for the passive-aggressive nature of my comment. It's just that the HN hive-mind has been quite snobbish towards budding developers of late and it has left a bad taste in my mouth. Personally, I believe that every developer who does a "Show HN" deserves at least one positive comment for every criticism they receive. YMMV, of course.