Sometimes I'll see a huge thread with many pages. I'll want to comment on the thread, but I'm not sure if I already did. It would be cool if there was something that said "Last comment by megadorkvikki on 09/09/14". This would only be visible to me. It's a small thing, but would save me time having to sift through pages of the thread. Let me know what you think.
50% support. There are two alternatives to this. At the side of the thread you will see your profile picture at the right bottom corner of the person who posted threads Avatar. That shows you if you have already commented. Another way is to use the search function where you can put the title of your thread and your forum name and it will show the comment by you. Both valid solutions to me.
I would 100% Support this idea but as Krissy said you can see your avatar if you have commented on the thread
That's True. It still isn't really necessarily needed as you could just check every page but if Cyp could add this it would make it a lot easier too see last time you commented on a certain thread.