Myself, I see the reputation I receive as a way to tune my posting style to match the forum, especially given that with a purely text-based medium you lose a lot of information. For example, if it's not blatently obvious that a post is a joke from the text then people may take it seriously (with all the drama that entails), as they don't have any body language or tone of voice to use to judge it. It's already had an effect on my posting, and I imagine it's change the posting styles of some other members as well.

At the moment reputation has no effect on forum privileges or abilities (with the exception that you must have positive reputation to use the feature), though I'm vageuly considering adding bonuses for high rep and penalties for low rep. For example, a low rep could disable someone's signature, while a high rep could permit you to change your rank (the bit below your name that says "JCF Member"), grant access to a restricted board, permit attachments... there's lots of options. Alternatively, it may be possible to award privileges for giving out reputation (rather than having a specific reputation) to encourage the use of it.

I personally see no need to regulate the giving out and receiving of reputation. The forum software has limits in place to try and prevent abuse by requiring you to spread the reputation among multiple users and rate-limiting the giving of reputation. Should someone manage to abuse it despite that then we can take action, though the main issue I can think of is using it to send supposedly anonymous abusive messages. I don't necessarily see persistently down/upvoting someone as an issue, as you'd have to spread the reputation among multiple users and it woudn't really achieve anything (though again, action can be taken if it gets ridiculous).