The forum has always had a "Karma" feature built into it but, as old timers may remember, when I enabled it back in the beginning it was quickly abused and degenerated into smiting wars, etc. It became a nuisance so I disabled it and have never considered turning it back on. We don't need a repeat of that nonsense.
But...
Personally, I tend to lurk on the site. I read most of your posts and discussions here, even though I rarely take part. A lot of times I read something that I like and want to give a thumbs up to without having to post a separate comment in the thread. Today I came across a mod for the forum (called, appropriately enough, "Like Posts") which lets users do just that.
In any post that appear in any of the "General Boards" or "Links", logged in members will see a red "Like" text button at the bottom of the post (just above the poster's signature, if there is one). You should also see one on the message index page for those boards, which will let you Like the topic itself. If you click on a Like button, it will change to Unlike to give the option of changing your mind. Liking a post or topic recommends it to other users, and there is now a "Like Stats" page (last item on the right in the menu at the top of the page) which will show the post popular posts, etc.
NOTE: You won't see a Like button on your own topics and posts.