Recently, I discovered a way to manipulate the current flagging system so that I can raise my own flag weight.
It all began innocently enough. I looked through my downvoted answers and saw an answer of mine that that was pretty lame and qualified as "not an answer". I flagged it, but then I realized I could delete it myself, so I deleted it. Then I figured it would be confusing to a moderator to see a flag for a deleted answer, so I undeleted it.
I then went to my profile, and noticed that my flag weight had already gone up. Mods had never accepted a flag this quickly before, so I figured that deleting a post validates the flags put on it. Noting this, I went back and deleted the answer.
Naturally, of course, this made me realize that I could increase my own flag weight by repeating this process:
flag my own post with a score of 0 or less
delete that post.
(optional) undelete the post
I did this a few times to make sure it wasn't a fluke, and then I kept doing it because I was greedy and wanted moar flag weightz. Then I just couldn't resist the temptation of posting "gigglewaffles" as an answer to a question, flagging it (with the message "blah blah blah"), and then deleting it.
It's a kind of boring process, so I stopped once my flag weight reached the nearest round number (which happened to be 500. I got the deputy badge because of dishonesty! Whoot whoot!).
I'm pretty sure this is a hole in the flag weight system. I'm not sure how you should fix it, but I'm thinking that if somebody flags his own post and then deletes it, the flag should be ignored.
If this isn't fixed very soon, I can foresee that some people who have read this post will follow this process for hours to get the max flag weight (750, I believe?).
(I know that flag weight isn't all that important, but I really enjoy seeing a number associated with my name increasing. If it weren't for that, I would never flag posts or answer questions. Please don't suck the challenge out of it for me.)