I haven't had time to review this whole thread since it was started a while ago. But I'm a wreck diver in the NE and spend most of my time on a boat this is what I carry while diving:

1.) Serated sheepfoot knife (UK Remora) in a sheath mounted on my harness waist strap
2.) EMT Shears mounted in a sheath next to the knife
3.) Wreck reel (Halcyon) w/ 400' of line
4.) Safty Spool w/ 250' of line clipped off in drysuit pocket
5.) 100 lb yellow lift bag/surface maker (Carter) (it looks like a big safty sausage it's about 10' tall)
6.) Back Up tables in wetnotes
7.) Storm Whistle cliped off in dry suit pocket
8.) Stainless Steel signal mirror clipped off in drysuit pocket
9.) 2 backup twist on lights w/ focusable lenses
10.) Compass w/ bezel
11.) All the normal scuba equipement plus what ever is needed for this particular dive.
12.) A GOOD BUDDY!

I would consider flares and marker dye if I was way offshore we dive a few wrecks which are 50+ miles out but flares and dye have limited value.

As for the "Spare Air" it's not a total waste of money but close <img src="images/graemlins/laugh.gif" alt="" /> - in the area I dive in we've nick named it "3 breaths 'till death". I'm not totally dismissing this a usefull piece of equipement but a pony tank setup or a set of doubles will give you a real back up instead of something that looks good.

You could carry other equipement but if you use a dependable dive boat for your trips EPIRB's and personal life rafts should not be needed. If your past due the boat should preform a search for you.

So how was your class?

You should visit this link, as it shows the basic scuba gear needed.

http://www.wkpp.org/articles/Gear/gearlist.htm