Replies count the same as posts on earning your "ranch hand" tag.
Current bartenders will notice that somebody is being especially helpful and will nominate that person as a bartender. Other bartenders then check out that person's posts. If another bartender agrees, then sheriff Jim Yingst will give the nominee an invitation to be a bartender.
We have had some people join the bartender ranks in other ways. Sometimes they come up with a great idea for a new forum and agree to do all the hard work to get that forum rolling. Sometimes, they compose new content for the static pages that we all agree is high quality stuff - it gets added to the ranch, and that person becomes a bartender.
I guess the key is that we are all volunteers here. If you are caught in the act of helping out, we wanna take some barriers away!