I've been wanting to add this feature since I added acorns to the site and it's now finished!
Now to reward people for a particularly good contribution, in addition to giving them a thumbs up, you can show your SUPER appreciation by giving a publicly viewable acorn tip to that member! Just click on the acorn icon next to the thumb icon. It'll ask you how much you want to send and off you go.
First person to reply to this post will get a tip from me.