As in  people that actually compete.  I've been thinking about trying out a single lift bench competition but I know almost nothing about it. What do I need to know before jumping into it?  I've done one before, but it was just a small, on post type thing that I literally walked out of a meeting, saw they were doing one in the gym and 10 minuted later I was "competing."

Looking online, a group called Raw Powerlifting has a competition local to me in July.

Go to the federation's webpage and read through their rule book. Each federation tends to have their own small rules that are specific to their competitions (ie wrist wrap thumb loops on/off, heels touching floor during bench, etc). As for a bench only meet, at a minimum you'll need to become used to benching with a pause on the chest, usually 1-1.5 seconds depending on the head judge.

I used to always bitch about how long the pauses were in competition. Then I actually started doing pauses in training and all of the sudden it wasn't bad at all. A few weeks out from the meet it is best to team up with someone who is familiar with powerlifting and get used to lifting with the commands. It really sucks to lift a weight and not get credit for it because you didn't wait for the command.

So, how much can you bench?

I don't even know my 1rep max right now. I've been doing it at the end of my workout. Yesterday for bench, after warming up I did 205x21, 285x5, 320x 2, and 340x1.
Eta; body weight is 219 right now at 6'2.

You might want to consider doing less reps at 205 and more at 285 - 300. Work on getting them up to 10 reps. Kind of like laying on a solid base. It should allow you get more at 320 as time goes on and to blow right by 340. I find this works for me .

I am kicking around doing a comp in June. :)

I competed for quite a while from 14-24 I was pretty good at it. I did full meets, bench only and push pull probably averaged 2-3 meets a year. Rules will vary with organizations, so until you look at their specific rules its hard to tell. Some basic things to consider...

- you will need a singlet.
- your butt must stay in contact with the bench thought the lift.
- you must pause on your chest (this is supposed to be the bar is motionless not a specific time ..1 second 2 second.
- you need to take the bar out at arms length or full extension
- your head may or may not need to stay in contact with the bench
- you will receive 2 or 3 commands depending on the organization (Start, Press, Rack) or (No start command, Press, Rack)
- your feet may or many not need to be flat on the floor
- your feet cannot shift or move around once the lift has started  
- some organizations will allow suicide (thumb less grip) and some require you to wrap your thumb
- if you use wrist wraps most will require you to remove the thumb loop from your thumb
- your spotter my or may not be able to give you a soft hand off aka guide the bar down

This is about all I can think of  for now and for reference I have in AAU, SPF, APF, USAPL, APA and SLP.

Do it now.  Sign up and thank me later.  Do the full power though and not the bench only.

It'll boost your training intensity, you'll have a blast and you'll meet some awesome people.  Seriously, do it.