http://www.omsdive.com/lift-smb.html
Can anyone tell me how the 9'7" smb is inflated?
Second stage, inflator, manually, or CO2 cartridge?

It has a "duck-bill" flap (one way valve) inside the bottom.
If UW you could hold your reg under the open bottom and purge. At the surface you could hold the bottom over your mouth & blow into it.

Thanks, fugu,
so if I am understanding correctly, the "duck bill flap" holds air at the surface.
Is there any closure to the flap? or does the pressure close it?

it's a one way flap, keeps maybe 98% of the air in. You pull the string on the OPV to vent/empty it.

In addition to OMS you might look at these:

Carter http://carterbag.com/personalfloat.html

DAN surface signal kit
https://www.diversalertnetwork.org/eseries/source/orders/index.cfm?task=3&CATEGORY=FIRSTAID&PRODUCT_TYPE=SALES&SKU=641%2D1000&DESCRIPTION=First%2DAid%20%26%20Safety%20Equipment&FindSpec=&CFTOKEN=62423401&continue=1&SEARCH_TYPE=find

Halcyon http://www.halcyon.net/mc/dam.shtml

Zeagle http://zeagle.chainreactionweb.com/index.php?src=gendocs&link=Accy_signal_devices&category=Accessories

Thanks again,
I like the carter bags or the oms.
I am looking at the biggest ones I can find. The Zeagle setup is nice, just that it's shorter and looks like an ad.
With the carter or oms I would need a reel and storage. The reel is easy to find but I haven't seen a bag that I like. Unfortunatly my BC pockets are very small.

I have a Zeagle SMB, I am pretty happy with it. Occasionally use it to send up an anchor I found.

I've seen the Halcyon CO2 charged SMB first hand in use, and I'll have to say, I was pretty impressed. You can see them for quite a ways.

I like these from XS Scuba: http://www.divesports.com/mall/xsscuba_acc_AC070SMB.asp

It's 7' long and 6.5" fat.

I bought one of those 9 fter OMS sausages and it was huge. I returned it. The 6 fters work pretty good. I just bought a 50lb round-non-dumping lift bag with a overpressure relief valve. I am going to see what everyone on my boat thinks about this round bag compared to the 6 ft sausage. What I have found is the big sausages have two issues: 1. when you send them up they lay flat on their side, unless your hanging real hard on them while accending. Thus, they are not all as easy to see as you think. 2. When you get really far away from the boat, I'm not so sure a long skinny object is easier to see than a round fat object. I gaurantee the round is easier to see comparing to 6 fter laying on it's side. So it is a no brainer, that the boat is more likely to be there when you surface. The real question is: Once you surface, would it be easier to see the now held upright 6 fter, or the round, possibly held in the air on top of a speargun if neccessary? I thought about getting a 80lb lift round, but will try the 50 first as it is pretty easy to fill a 50 and let it fly without much hassle on the bottom. I'm not so sure about a 80lb lift bag?
I have realized a orange poly ball is alot easier to see, from far away, over a sausage, so I'm going to try the short fat round float vs the long skinny sausage. Who knows? I might be onto something! Most 6 ft sausages have the same 50lb lift capacity also.