So, yes you are able to make an empty comment as a bookmark for yourself that is visible to everyone. But, you should expect it to be downvoted to invisibility.
Edit: P.S. Usernames here are small and grey. Probably no one looked at your username before downvoting that first comment. If I made comments like the ones you've made I'd get downvoted too, because no one knows or cares that I have 26k karma.
For this you have Pocket[1], which has as a main benefit that it doesn't pollute the discussion for everyone else.
As an added bonus it even syncs the stuff offline on your phone and tablet!
No worries though. I won't be bothering you guys with my upvotes and comments any longer. You regulars can down vote everything I ever posted if you like. It's clear n00bs aren't welcome here. I won't be coming back to your site.
That's actually part of the point of making a story you upvote go into "saved stories": to encourage you to only upvote the stories you actually find interesting enough to return to.
I understand the desire to be able to find the post again; however, the fact remains that that's not what comments are designed for. You can't exactly blame other users for treating comments the way they were designed to be treated.
That said, I have to agree that being able to "bookmark" posts without having to risk being downvoted would be a useful feature. I've submitted an "Ask HN" post to see how many other users feel the same way: