What all of the fantastic mods have said above, but I have a few additions.
On how you get the position: When we need new moderators, we look for a few things: Fair minded folks with an even-keeled temperament. Well written, well rounded individuals. People who’ve been on the site for a while, and participate regularly (in other words, they’re invested in the site). Sometimes we want someone who has all of those qualities and is in a particular time-zone… helps close gaps in moderator coverage. (The mod team is international!) When we decide who would be a good fit for the mod team, we ask them if they’re interested in volunteering their time to keep Fluther in great shape. Usually, they foolishly agree. :p
Moderating can give you valuable job experience, worth listing on a resume, for sure. For me, personally, moderating has been a ‘stepping stone on a career path’, though I never imagined it would be. I joined Fluther a little over two years ago, and quickly fell in love with the site. After some time, I was asked to become a moderator, which I loved. You really feel like you’re making a difference on the site, which is great. When the two previous volunteer community managers stepped down, I was asked to take their place. I became the part-time ‘head moderator’, taking on many new duties. Very recently, Fluther offered me a full-time job with even more new duties. There’s an actual salary and everything! I now work for the site I love so much. How awesome is that? :D