My TT vest holds 1 G3 mag per rifle pouch.

You can also pick up a camel back knock off at MEC, I'd recommend just grabbing the bladder.

I use an Arktis 1601 assault vest, overal similar to the webtex i guess, design-wise.

4x mag pouches, hold 4 M16 mags each (can probably fit 3 G3 mags), or 2 AK74 mags (if you want it to close properly)
2x utility pouches (can hold a canteen or whatever other stuff)
2x small/first aid pouches
1x compass/multitool/pistol mag pouch
2x large/internal map pockets, one of which has a built-in holster

carries 12 locaps, leaving one mag pouch free to carry extra crap (extra bbs, gatoraide bottle). If I need a compass, I use a small USGI lensatic compass, which i can stick into one of the firstaid pouches. I keep a Leatherman-style multitool in the multitool pouch if I'm outdoors. I can either keep a 1L canteen in a utility pouch, or my platipus in the hydration pack carrier. First aid kit in the other utility pouch if I'm outdoors.

What exactly I carry really depends on when I'm playing and what gun i'm using (ie., i won't carry 40mm grenades if I'm not using the gun with the m203, i won't carry water if I'm never gonna be more than 100m from my backpack/basecamp, etc). Water is especially vicious; it's 1kg of weight for every liter of water you carry. So given the total weight of your loadout (gun, gear, etc) running around with 3L of water - an extra 3kg (almost 7 lbs) - in rough terrain, on a hot summer day, is going to make you more thirsty than if you just had a bottle of gatoraid with you to keep you hydrated.

Your LBV shouldn't be used as a ruck sack.

My vest, I just shove in 1 emergency P90 highcap on my back where the radio is supposed to go, a balaclava on the front, and my barrel plug is in there too =P. My other mags go in my drop leg pouch.

I wish I had a vest that could fit my P90 mags in the front.

Mags, BB's, Canteen, sometimes smoke grenade, food, sometimes a flashlight

are you talking about just vest or vest/belt combo?

try putting a rain jacket in one of the pouches but dont bother with rain pants. first aid kit of some sort even if its just bandaids, electrical tape/ducttape, if you have small smoke grenade pouches they hold chocolate bars real good, ammo lots of ammo some sort of loading device to load all your ammo, water it gets hot out there so dont be skimpy with it if you can get to a surpluss store by 2 canteens and find a place on the vest where you can get to them but arent in the way if you go prone.

I think thats about it for my$.02

In my belt kit I carry ammo, water and basic E&E kit (hexi stove, basic rations and "survival" stuff). Thats it thats all. If I need more I put it in my bergen and leave it at base.

The vest that Tom is wearing here can very comfortably fit four P90 mags on the front. It's also got what is I believe a radio pouch on the back that can hold another two. I've seen it for sale at local surplus stores for around $120. You might also want to PM Man Solo about buying his.