MySQL Database Load-Balancing for vBulletin?
 

Is such thing even possible? To have two identical databases load-balance one forum? It doesn't seem like this question has been asked before, but I would like to know if this is something vBulletin would allow. If so, does anyone have any ideas how to proceed into implementation?

Do you have a need for such a thing? If mysql queries are really hammering your server, you may want to purchase or use one more to serve as a dedicated DB server.

They're not, but I don't see how implementing a load-balancing database could do any harm, if its actually possible.

I'm not sure about load balancing but you could always have a look into cloud mysql hosting.

I have, but I'm looking rather to take advantage of the un-used DB slots I have rather than cloud hosting for $70/month (at which I can find a VPS provider to host the site and DB) :)

There is one advantage to having one server be a dedicated mysql server and that is you can tailor the hardware on that server for dbs. Since a forum has lots of reads/writes you could be SSD drives on the db machine while leaving the web server with a more reasonably priced hardware package.