[tucson]

How about some keyboard navigation shortcuts? (left-right arrows). It works on http://www.HnEasy.com.

[francesca]

emacs style editing in the text box

[daxelrod]

Shouldn't that be a browser feature, rather than every website creating their own different implementation?

[drcube]

https://addons.mozilla.org/en-US/firefox/addon/firemacs/

[cpr]

Use Safari/Chrome under Mac OS, and you've got it, complete with customizable key mappings.