Well howdy 0!
having a "OHAIGUYZ!" thread is ok. lots of people do it. and shoutbox isn't a viable option, cuz within seconds your hi is gone. He is saying hi, cuz he's a new recruit, and the application thread isn't 100% viable either cuz only people that read/look at those are usually people from THAT division. Though putting them in the Off Topic thread is usually a little better (even though introducing yourself is community related) cuz "spam" threads are looked down upon less there.