I have noticed that I can now share my answer on Facebook and Twitter, but I only have my friends on my Facebook and Twitter accounts, so surely by me sharing an answer I'm encouraging ring voting?
I'll elaborate a bit on my comment.
Our users are very good at bringing completely crap answers with an inordinate amount of up-votes to our attention, which sometimes leads to uncovering and breaking up voting rings.
That being said, you aren't just promoting yourself by sharing an answer. You're promoting the fact that you made the site a little bit more awesome than it was, which means you're also promoting the site. Bragging about the ownership you took in something is one of the best ways that something can be promoted.
By design, we reward great contributions with reputation, so I really don't see a possible negative there. I think that most people would not be inclined to share something that they didn't feel good about.
If you have a long standing track record of quality, there is no reason for a moderator to ever look at (or care about) voting patterns to and from your account. If you write something like this:
u can jst fix it like my bro did in dis blog post
... and it is subsequently up voted, I'm going to take a hard look at your account.
It seems like a two-edged sword: If the up-votes are warranted, I see little harm. If not, other respected contributors may be more likely to evaluate the answer critically. Should a pattern emerge, the result could be a worse reputation.
Public promotion of excellent questions or answers should be encouraged. It would improve both the content and the reputation of the site, and encourage the creation of a virtuous cycle of better content creation, improved reputation for the contributor, and improved reputation for the site in general.
Public promotion of poor content would hurt the value of the site, but even more-so, hurt the reputation of the contributor, which would be a moderating influence on such behavior.